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<button class="button is-small is-link">Go</button> </div> </div> </form> </div> </div> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a href="/search/?searchtype=author&query=Barnes%2C+G&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Barnes%2C+G&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Barnes%2C+G&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> <li> <a href="/search/?searchtype=author&query=Barnes%2C+G&start=100" class="pagination-link " aria-label="Page 3" aria-current="page">3 </a> </li> </ul> </nav> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.02695">arXiv:2409.02695</a> <span> [<a href="https://arxiv.org/pdf/2409.02695">pdf</a>, <a href="https://arxiv.org/format/2409.02695">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ad77a0">10.3847/1538-4357/ad77a0 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> How does the critical torus instability height vary with the solar cycle? </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=James%2C+A+W">Alexander W. James</a>, <a href="/search/astro-ph?searchtype=author&query=Green%2C+L+M">Lucie M. Green</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+G">Graham Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=van+Driel-Gesztelyi%2C+L">Lidia van Driel-Gesztelyi</a>, <a href="/search/astro-ph?searchtype=author&query=Williams%2C+D+R">David R. Williams</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2409.02695v1-abstract-short" style="display: inline;"> The ideal magnetohydrodynamic torus instability can drive the eruption of coronal mass ejections. The critical threshold of magnetic field strength decay for the onset of the torus instability occurs at different heights in different solar active regions, and understanding this variation could therefore improve space weather prediction. In this work, we aim to find out how the critical torus insta… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.02695v1-abstract-full').style.display = 'inline'; document.getElementById('2409.02695v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.02695v1-abstract-full" style="display: none;"> The ideal magnetohydrodynamic torus instability can drive the eruption of coronal mass ejections. The critical threshold of magnetic field strength decay for the onset of the torus instability occurs at different heights in different solar active regions, and understanding this variation could therefore improve space weather prediction. In this work, we aim to find out how the critical torus instability height evolves throughout the solar activity cycle. We study a significant subset of HMI and MDI Space-Weather HMI Active Region Patches (SHARPs and SMARPs) from 1996-2023, totalling 21584 magnetograms from 4436 unique active region patches. For each magnetogram, we compute the critical height averaged across the main polarity inversion line, the total unsigned magnetic flux and the separation between the positive and negative magnetic polarities. We find the critical height in active regions varies with the solar cycle, with higher (lower) average critical heights observed around solar maximum (minimum). We conclude this is because the critical height is proportional to the separation between opposite magnetic polarities, which in turn is proportional to the total magnetic flux in a region, and more magnetic regions with larger fluxes and larger sizes are observed at solar maximum. This result is noteworthy because, despite the higher critical heights, more CMEs are observed around solar maximum than at solar minimum. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.02695v1-abstract-full').style.display = 'none'; document.getElementById('2409.02695v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted to ApJ. 14 pages, 6 Figures, 1 Table</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.05687">arXiv:2305.05687</a> <span> [<a href="https://arxiv.org/pdf/2305.05687">pdf</a>, <a href="https://arxiv.org/format/2305.05687">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/accc89">10.3847/1538-4357/accc89 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Coronal Heating as Determined by the Solar Flare Frequency Distribution Obtained by Aggregating Case Studies </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Mason%2C+J+P">James Paul Mason</a>, <a href="/search/astro-ph?searchtype=author&query=Werth%2C+A">Alexandra Werth</a>, <a href="/search/astro-ph?searchtype=author&query=West%2C+C+G">Colin G. West</a>, <a href="/search/astro-ph?searchtype=author&query=Youngblood%2C+A+A">Allison A. Youngblood</a>, <a href="/search/astro-ph?searchtype=author&query=Woodraska%2C+D+L">Donald L. Woodraska</a>, <a href="/search/astro-ph?searchtype=author&query=Peck%2C+C">Courtney Peck</a>, <a href="/search/astro-ph?searchtype=author&query=Lacjak%2C+K">Kevin Lacjak</a>, <a href="/search/astro-ph?searchtype=author&query=Frick%2C+F+G">Florian G. Frick</a>, <a href="/search/astro-ph?searchtype=author&query=Gabir%2C+M">Moutamen Gabir</a>, <a href="/search/astro-ph?searchtype=author&query=Alsinan%2C+R+A">Reema A. Alsinan</a>, <a href="/search/astro-ph?searchtype=author&query=Jacobsen%2C+T">Thomas Jacobsen</a>, <a href="/search/astro-ph?searchtype=author&query=Alrubaie%2C+M">Mohammad Alrubaie</a>, <a href="/search/astro-ph?searchtype=author&query=Chizmar%2C+K+M">Kayla M. Chizmar</a>, <a href="/search/astro-ph?searchtype=author&query=Lau%2C+B+P">Benjamin P. Lau</a>, <a href="/search/astro-ph?searchtype=author&query=Dominguez%2C+L+M">Lizbeth Montoya Dominguez</a>, <a href="/search/astro-ph?searchtype=author&query=Price%2C+D">David Price</a>, <a href="/search/astro-ph?searchtype=author&query=Butler%2C+D+R">Dylan R. Butler</a>, <a href="/search/astro-ph?searchtype=author&query=Biron%2C+C+J">Connor J. Biron</a>, <a href="/search/astro-ph?searchtype=author&query=Feoktistov%2C+N">Nikita Feoktistov</a>, <a href="/search/astro-ph?searchtype=author&query=Dewey%2C+K">Kai Dewey</a>, <a href="/search/astro-ph?searchtype=author&query=Loomis%2C+N+E">N. E. Loomis</a>, <a href="/search/astro-ph?searchtype=author&query=Bodzianowski%2C+M">Michal Bodzianowski</a>, <a href="/search/astro-ph?searchtype=author&query=Kuybus%2C+C">Connor Kuybus</a>, <a href="/search/astro-ph?searchtype=author&query=Dietrick%2C+H">Henry Dietrick</a>, <a href="/search/astro-ph?searchtype=author&query=Wolfe%2C+A+M">Aubrey M. Wolfe</a> , et al. (977 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2305.05687v1-abstract-short" style="display: inline;"> Flare frequency distributions represent a key approach to addressing one of the largest problems in solar and stellar physics: determining the mechanism that counter-intuitively heats coronae to temperatures that are orders of magnitude hotter than the corresponding photospheres. It is widely accepted that the magnetic field is responsible for the heating, but there are two competing mechanisms th… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.05687v1-abstract-full').style.display = 'inline'; document.getElementById('2305.05687v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.05687v1-abstract-full" style="display: none;"> Flare frequency distributions represent a key approach to addressing one of the largest problems in solar and stellar physics: determining the mechanism that counter-intuitively heats coronae to temperatures that are orders of magnitude hotter than the corresponding photospheres. It is widely accepted that the magnetic field is responsible for the heating, but there are two competing mechanisms that could explain it: nanoflares or Alfv茅n waves. To date, neither can be directly observed. Nanoflares are, by definition, extremely small, but their aggregate energy release could represent a substantial heating mechanism, presuming they are sufficiently abundant. One way to test this presumption is via the flare frequency distribution, which describes how often flares of various energies occur. If the slope of the power law fitting the flare frequency distribution is above a critical threshold, $伪=2$ as established in prior literature, then there should be a sufficient abundance of nanoflares to explain coronal heating. We performed $>$600 case studies of solar flares, made possible by an unprecedented number of data analysts via three semesters of an undergraduate physics laboratory course. This allowed us to include two crucial, but nontrivial, analysis methods: pre-flare baseline subtraction and computation of the flare energy, which requires determining flare start and stop times. We aggregated the results of these analyses into a statistical study to determine that $伪= 1.63 \pm 0.03$. This is below the critical threshold, suggesting that Alfv茅n waves are an important driver of coronal heating. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.05687v1-abstract-full').style.display = 'none'; document.getElementById('2305.05687v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">1,002 authors, 14 pages, 4 figures, 3 tables, published by The Astrophysical Journal on 2023-05-09, volume 948, page 71</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2302.06496">arXiv:2302.06496</a> <span> [<a href="https://arxiv.org/pdf/2302.06496">pdf</a>, <a href="https://arxiv.org/format/2302.06496">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/acba8e">10.3847/1538-4357/acba8e <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Implications of Different Solar Photospheric Flux-Transport Models for Global Coronal and Heliospheric Modeling </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+G">Graham Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=DeRosa%2C+M+L">Marc L. DeRosa</a>, <a href="/search/astro-ph?searchtype=author&query=Jones%2C+S+I">Shaela I. Jones</a>, <a href="/search/astro-ph?searchtype=author&query=Arge%2C+C+N">Charles N. Arge</a>, <a href="/search/astro-ph?searchtype=author&query=Henney%2C+C+J">Carl J. Henney</a>, <a href="/search/astro-ph?searchtype=author&query=Cheung%2C+M+C+M">Mark C. M. Cheung</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2302.06496v1-abstract-short" style="display: inline;"> The concept of surface-flux transport (SFT) is commonly used in evolving models of the large-scale solar surface magnetic field. These photospheric models are used to determine the large-scale structure of the overlying coronal magnetic field, as well as to make predictions about the fields and flows that structure the solar wind. We compare predictions from two SFT models for the solar wind, open… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.06496v1-abstract-full').style.display = 'inline'; document.getElementById('2302.06496v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.06496v1-abstract-full" style="display: none;"> The concept of surface-flux transport (SFT) is commonly used in evolving models of the large-scale solar surface magnetic field. These photospheric models are used to determine the large-scale structure of the overlying coronal magnetic field, as well as to make predictions about the fields and flows that structure the solar wind. We compare predictions from two SFT models for the solar wind, open magnetic field footpoints, and the presence of coronal magnetic null points throughout various phases of a solar activity cycle, focusing on the months of April in even-numbered years between 2012 and 2020, inclusive. We find that there is a solar cycle dependence to each of the metrics considered, but there is not a single phase of the cycle in which all the metrics indicate good agreement between the models. The metrics also reveal large, transient differences between the models when a new active region is rotating into the assimilation window. The evolution of the surface flux is governed by a combination of large scale flows and comparatively small scale motions associated with convection. Because the latter flows evolve rapidly, there are intervals during which their impact on the surface flux can only be characterized in a statistical sense, thus their impact is modeled by introducing a random evolution that reproduces the typical surface flux evolution. We find that the differences between the predicted properties are dominated by differences in the model assumptions and implementation, rather than selection of a particular realization of the random evolution. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.06496v1-abstract-full').style.display = 'none'; document.getElementById('2302.06496v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in The Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2212.11255">arXiv:2212.11255</a> <span> [<a href="https://arxiv.org/pdf/2212.11255">pdf</a>, <a href="https://arxiv.org/ps/2212.11255">ps</a>, <a href="https://arxiv.org/format/2212.11255">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ac9c04">10.3847/1538-4357/ac9c04 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Properties of Flare-Imminent versus Flare-Quiet Active Regions from the Chromosphere through the Corona II: NonParametric Discriminant Analysis Results from the NWRA Classification Infrastructure (NCI) </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Leka%2C+K">KD Leka</a>, <a href="/search/astro-ph?searchtype=author&query=Dissauer%2C+K">Karin Dissauer</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+G">Graham Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Wagner%2C+E+L">Eric L. Wagner</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2212.11255v1-abstract-short" style="display: inline;"> A large sample of active-region-targeted time-series images from the Solar Dynamics Observatory / Atmospheric Imaging Assembly, the AIA Active Region Patch database ("AARPs", Paper I: Dissauer et al 2022) is used to investigate whether parameters describing the coronal, transition region, and chromospheric emission can differentiate a region that will imminently produce a solar flare from one that… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.11255v1-abstract-full').style.display = 'inline'; document.getElementById('2212.11255v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2212.11255v1-abstract-full" style="display: none;"> A large sample of active-region-targeted time-series images from the Solar Dynamics Observatory / Atmospheric Imaging Assembly, the AIA Active Region Patch database ("AARPs", Paper I: Dissauer et al 2022) is used to investigate whether parameters describing the coronal, transition region, and chromospheric emission can differentiate a region that will imminently produce a solar flare from one that will not. Parametrizations based on moment analysis of direct and running-difference images provide for physically-interpretable results from nonparametric discriminant analysis. Across four event definitions including both 24hr and 6hr validity periods, 160 image-based parameters capture the general state of the atmosphere, rapid brightness changes, and longer-term intensity evolution. We find top Brier Skill Scores in the 0.07--0.33 range, True Skill Statistics in the 0.68--0.82 range (both depending on event definition), and Receiver Operating Characteristic Skill Scores above 0.8. Total emission can perform notably as can steeply increasing or decreasing brightness, although mean brightness measures do not, demonstrating the well-known active-region-size/flare-productivity relation. Once a region is flare productive, the active-region coronal plasma appears to stay hot. The 94AA filter data provides the most parameters with discriminating power, with indications that it benefits from sampling multiple physical regimes. In particular, classification success using higher-order moments of running difference images indicate a propensity for flare-imminent regions to display short-lived small-scale brightening events. Parameters describing the evolution of the corona can provide flare-imminent indicators, but at no preference over "static" parameters. Finally, all parameters and NPDA-derived probabilities are available to the community for additional research. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.11255v1-abstract-full').style.display = 'none'; document.getElementById('2212.11255v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Astrophysical Journal, in press</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2209.15036">arXiv:2209.15036</a> <span> [<a href="https://arxiv.org/pdf/2209.15036">pdf</a>, <a href="https://arxiv.org/format/2209.15036">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/aca539">10.3847/1538-4365/aca539 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Large-Scale Spatial Cross-Calibration of Hinode/SOT-SP and SDO/HMI </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Fouhey%2C+D+F">David F. Fouhey</a>, <a href="/search/astro-ph?searchtype=author&query=Higgins%2C+R+E+L">Richard E. L. Higgins</a>, <a href="/search/astro-ph?searchtype=author&query=Antiochos%2C+S+K">Spiro K. Antiochos</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+G">Graham Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=DeRosa%2C+M+L">Marc L. DeRosa</a>, <a href="/search/astro-ph?searchtype=author&query=Hoeksema%2C+J+T">J. Todd Hoeksema</a>, <a href="/search/astro-ph?searchtype=author&query=Leka%2C+K+D">K. D. Leka</a>, <a href="/search/astro-ph?searchtype=author&query=Liu%2C+Y">Yang Liu</a>, <a href="/search/astro-ph?searchtype=author&query=Schuck%2C+P+W">Peter W. Schuck</a>, <a href="/search/astro-ph?searchtype=author&query=Gombosi%2C+T+I">Tamas I. Gombosi</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2209.15036v1-abstract-short" style="display: inline;"> We investigate the cross-calibration of the Hinode/SOT-SP and SDO/HMI instrument meta-data, specifically the correspondence of the scaling and pointing information. Accurate calibration of these datasets gives the correspondence needed by inter-instrument studies and learning-based magnetogram systems, and is required for physically-meaningful photospheric magnetic field vectors. We approach the p… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.15036v1-abstract-full').style.display = 'inline'; document.getElementById('2209.15036v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2209.15036v1-abstract-full" style="display: none;"> We investigate the cross-calibration of the Hinode/SOT-SP and SDO/HMI instrument meta-data, specifically the correspondence of the scaling and pointing information. Accurate calibration of these datasets gives the correspondence needed by inter-instrument studies and learning-based magnetogram systems, and is required for physically-meaningful photospheric magnetic field vectors. We approach the problem by robustly fitting geometric models on correspondences between images from each instrument's pipeline. This technique is common in computer vision, but several critical details are required when using scanning slit spectrograph data like Hinode/SOT-SP. We apply this technique to data spanning a decade of the Hinode mission. Our results suggest corrections to the published Level 2 Hinode/SOT-SP data. First, an analysis on approximately 2,700 scans suggests that the reported pixel size in Hinode/SOT-SP Level 2 data is incorrect by around 1%. Second, analysis of over 12,000 scans show that the pointing information is often incorrect by dozens of arcseconds with a strong bias. Regression of these corrections indicates that thermal effects have caused secular and cyclic drift in Hinode/SOT-SP pointing data over its mission. We offer two solutions. First, direct co-alignment with SDO/HMI data via our procedure can improve alignments for many Hinode/SOT-SP scans. Second, since the pointing errors are predictable, simple post-hoc corrections can substantially improve the pointing. We conclude by illustrating the impact of this updated calibration on derived physical data products needed for research and interpretation. Among other things, our results suggest that the pointing errors induce a hemispheric bias in estimates of radial current density. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.15036v1-abstract-full').style.display = 'none'; document.getElementById('2209.15036v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 September, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Under revisions at ApJS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2204.09759">arXiv:2204.09759</a> <span> [<a href="https://arxiv.org/pdf/2204.09759">pdf</a>, <a href="https://arxiv.org/format/2204.09759">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-3881/ac68ed">10.3847/1538-3881/ac68ed <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The eta Aquilae System: Radial Velocities and Astrometry in Search of eta Aql B </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Benedict%2C+G+F">G. Fritz Benedict</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+T+G">Thomas G. Barnes III</a>, <a href="/search/astro-ph?searchtype=author&query=Evans%2C+N+R">Nancy R. Evans</a>, <a href="/search/astro-ph?searchtype=author&query=Cochran%2C+W+D">William D. Cochran</a>, <a href="/search/astro-ph?searchtype=author&query=Anderson%2C+R+I">Richard I. Anderson</a>, <a href="/search/astro-ph?searchtype=author&query=McArthur%2C+B+E">Barbara E. McArthur</a>, <a href="/search/astro-ph?searchtype=author&query=Harrison%2C+T+E">Thomas E. Harrison</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2204.09759v1-abstract-short" style="display: inline;"> The classical Cepheid eta Aql was not included in past Leavitt Law work (Benedict et al. 2007) because of a presumed complicating orbit due to a known B9.8V companion. To determine the orbit of eta Aql B, we analyze a significant number of radial velocity measures (RV) from eight sources. With these we establish the RV variation due to Cepheid pulsation, using a twelve Fourier coefficient model, w… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.09759v1-abstract-full').style.display = 'inline'; document.getElementById('2204.09759v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2204.09759v1-abstract-full" style="display: none;"> The classical Cepheid eta Aql was not included in past Leavitt Law work (Benedict et al. 2007) because of a presumed complicating orbit due to a known B9.8V companion. To determine the orbit of eta Aql B, we analyze a significant number of radial velocity measures (RV) from eight sources. With these we establish the RV variation due to Cepheid pulsation, using a twelve Fourier coefficient model, while solving for velocity offsets required to bring the RV data sets into coincidence. RV residuals provide no evidence of orbital motion, suggesting either nearly face-on orientation or very long period. Reanalysis of Hubble Space Telescope Fine Guidance Sensor astrometry now includes reference star parallax and proper motion priors from Gaia EDR3. As modeling confirmation, we reanalyze zeta Gem in parallel, deriving zeta Gem parallax and proper motion values consistent with Gaia EDR3, and consistent with the Benedict 2007 Leavitt Law. In an effort to further characterize eta Aql B, we hypothesize that eta Aql residuals larger than those of the associated reference stars or a parallax inconsistent with EDR3 and the Benedict 2007 Leavitt Law indicate unmodeled orbital motion. Using the astrometric noise or parallax mismatch with EDR3 we estimate possible periods and mass for eta Aql B. Ascribing photocenter motion to the photometric variation of the Cepheid, eta Aql A, yields a plausible separation, consistent with a long period, explaining the lack of RV variation. None of these approaches yields an unassailable characterization of the eta Aql A-B system <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.09759v1-abstract-full').style.display = 'none'; document.getElementById('2204.09759v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 April, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">to appear in The Astronomical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2108.12421">arXiv:2108.12421</a> <span> [<a href="https://arxiv.org/pdf/2108.12421">pdf</a>, <a href="https://arxiv.org/format/2108.12421">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ac42d5">10.3847/1538-4365/ac42d5 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> SynthIA: A Synthetic Inversion Approximation for the Stokes Vector Fusing SDO and Hinode into a Virtual Observatory </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Higgins%2C+R+E+L">Richard E. L. Higgins</a>, <a href="/search/astro-ph?searchtype=author&query=Fouhey%2C+D+F">David F. Fouhey</a>, <a href="/search/astro-ph?searchtype=author&query=Antiochos%2C+S+K">Spiro K. Antiochos</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+G">Graham Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Cheung%2C+M+C+M">Mark C. M. Cheung</a>, <a href="/search/astro-ph?searchtype=author&query=Hoeksema%2C+J+T">J. Todd Hoeksema</a>, <a href="/search/astro-ph?searchtype=author&query=Leka%2C+K">KD Leka</a>, <a href="/search/astro-ph?searchtype=author&query=Liu%2C+Y">Yang Liu</a>, <a href="/search/astro-ph?searchtype=author&query=Schuck%2C+P+W">Peter W. Schuck</a>, <a href="/search/astro-ph?searchtype=author&query=Gombosi%2C+T+I">Tamas I. Gombosi</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2108.12421v1-abstract-short" style="display: inline;"> Both NASA's Solar Dynamics Observatory (SDO) and the JAXA/NASA Hinode mission include spectropolarimetric instruments designed to measure the photospheric magnetic field. SDO's Helioseismic and Magnetic Imager (HMI) emphasizes full-disk high-cadence and good spatial resolution data acquisition while Hinode's Solar Optical Telescope Spectro-Polarimeter (SOT-SP) focuses on high spatial resolution an… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.12421v1-abstract-full').style.display = 'inline'; document.getElementById('2108.12421v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2108.12421v1-abstract-full" style="display: none;"> Both NASA's Solar Dynamics Observatory (SDO) and the JAXA/NASA Hinode mission include spectropolarimetric instruments designed to measure the photospheric magnetic field. SDO's Helioseismic and Magnetic Imager (HMI) emphasizes full-disk high-cadence and good spatial resolution data acquisition while Hinode's Solar Optical Telescope Spectro-Polarimeter (SOT-SP) focuses on high spatial resolution and spectral sampling at the cost of a limited field of view and slower temporal cadence. This work introduces a deep-learning system named SynthIA (Synthetic Inversion Approximation), that can enhance both missions by capturing the best of each instrument's characteristics. We use SynthIA to produce a new magnetogram data product, SynodeP (Synthetic Hinode Pipeline), that mimics magnetograms from the higher spectral resolution Hinode/SOT-SP pipeline, but is derived from full-disk, high-cadence, and lower spectral-resolution SDO/HMI Stokes observations. Results on held-out data show that SynodeP has good agreement with the Hinode/SOT-SP pipeline inversions, including magnetic fill fraction, which is not provided by the current SDO/HMI pipeline. SynodeP further shows a reduction in the magnitude of the 24-hour oscillations present in the SDO/HMI data. To demonstrate SynthIA's generality, we show the use of SDO/AIA data and subsets of the HMI data as inputs, which enables trade-offs between fidelity to the Hinode/SOT-SP inversions, number of observations used, and temporal artifacts. We discuss possible generalizations of SynthIA and its implications for space weather modeling. This work is part of the NASA Heliophysics DRIVE Science Center (SOLSTICE) at the University of Michigan under grant NASA 80NSSC20K0600E, and will be open-sourced. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.12421v1-abstract-full').style.display = 'none'; document.getElementById('2108.12421v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2107.07568">arXiv:2107.07568</a> <span> [<a href="https://arxiv.org/pdf/2107.07568">pdf</a>, <a href="https://arxiv.org/format/2107.07568">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202140818">10.1051/0004-6361/202140818 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Pulsational instability of pre-main sequence models from accreting protostars. I. Constraining the input physics for accretion with spectroscopic parameters and stellar pulsations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Steindl%2C+T">T. Steindl</a>, <a href="/search/astro-ph?searchtype=author&query=Zwintz%2C+K">K. Zwintz</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+T+G">T. G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Muellner%2C+M">M. Muellner</a>, <a href="/search/astro-ph?searchtype=author&query=Vorobyov%2C+E+I">E. I. Vorobyov</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2107.07568v1-abstract-short" style="display: inline;"> Context: The pre-main sequence evolution is often simplified by choosing classical initial models. These have large initial radii and sufficient uniform contraction to make them fully convective. Contrary to that, real stars are born as small protostellar seeds in collapsing molecular clouds and obtain their final mass by means of accretion. Aims: We aim to constrain the input physics of accretion… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.07568v1-abstract-full').style.display = 'inline'; document.getElementById('2107.07568v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2107.07568v1-abstract-full" style="display: none;"> Context: The pre-main sequence evolution is often simplified by choosing classical initial models. These have large initial radii and sufficient uniform contraction to make them fully convective. Contrary to that, real stars are born as small protostellar seeds in collapsing molecular clouds and obtain their final mass by means of accretion. Aims: We aim to constrain the input physics of accretion on protostellar seeds with observed spectroscopic parameters and stellar pulsations of young stellar objects and pre-main sequence stars. Methods: We conducted a literature search for spectroscopic samples of young stellar objects and pre-main sequence stars including all previously known pulsators. The sample size of pulsating pre-main sequence stars is increased by analysing TESS observations and presenting discoveries in CoRoT data. We employ MESA and GYRE to calculate evolutionary tracks of accreting protostellar seeds in a constant accretion scenario, the subsequent pre-main sequence evolution, and their pulsation properties. The results are then compared with observations to constrain the input physics. Results: We discuss 16 formerly unknown pulsating pre-main sequence stars and candidates that are either of SPB, $未$ Scuti,$纬$ Doradus or $未$ Scuti - $纬$ Doradus hybrid type. We find that evolutionary tracks with a mass accretion rate of $5\times10^{-6} M_\odot/{\rm yr}$ and fraction of injected accretion energy of $尾=0.1$ provide the best results in enveloping the spectroscopic parameters of pre-main sequence stars in a constant accretion scenario. The calculated instability regions constrain the atmospheric boundary conditions to Eddington Gray atmospheres; we discuss the future potential for additional constraints by instability regions that are dependent on radial order. We present a possible candidate for pulsations in M-type young stellar objects. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.07568v1-abstract-full').style.display = 'none'; document.getElementById('2107.07568v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 July, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">21 pages plus 12 for the appendix, 17 figures plus 27 for the appendix, accepted for publication in Astronomy & Astrophysics</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 654, A36 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2106.05208">arXiv:2106.05208</a> <span> [<a href="https://arxiv.org/pdf/2106.05208">pdf</a>, <a href="https://arxiv.org/ps/2106.05208">ps</a>, <a href="https://arxiv.org/format/2106.05208">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-3881/ac09f2">10.3847/1538-3881/ac09f2 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A Radial Velocity Search for Binary RR Lyrae Variables </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+T+G">Thomas G. Barnes III</a>, <a href="/search/astro-ph?searchtype=author&query=Guggenberger%2C+E">Elisabeth Guggenberger</a>, <a href="/search/astro-ph?searchtype=author&query=Kolenberg%2C+K">Katrien Kolenberg</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2106.05208v1-abstract-short" style="display: inline;"> We report 272 radial velocities for 19 RR Lyrae variables. For most of the stars we have radial velocities for the complete pulsation cycle. These data are used to determine robust center--of--mass radial velocities that have been compared to values from the literature in a search for evidence of binary systems. Center--of--mass velocities were determined for each star using Fourier Series and Tem… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.05208v1-abstract-full').style.display = 'inline'; document.getElementById('2106.05208v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2106.05208v1-abstract-full" style="display: none;"> We report 272 radial velocities for 19 RR Lyrae variables. For most of the stars we have radial velocities for the complete pulsation cycle. These data are used to determine robust center--of--mass radial velocities that have been compared to values from the literature in a search for evidence of binary systems. Center--of--mass velocities were determined for each star using Fourier Series and Template fits to the radial velocities. Our center--of--mass velocities have uncertainties from $\pm0.16$ km s$^{-1}$ to $\pm$2.5 km s$^{-1}$, with a mean uncertainty of $\pm$0.92 km s$^{-1}$. We combined our center--of--mass velocities with values from the literature to look for deviations from the mean center--of--mass velocity of each star. Fifteen RR Lyrae show no evidence of binary motion (BK And, CI And, Z CVn, DM Cyg, BK Dra, RR Gem, XX Hya, SZ Leo, BX Leo, TT Lyn, CN Lyr, TU Per, U Tri, RV UMa, and AV Vir). In most cases this conclusion is reached due to the sporadic sampling of the center--of--mass velocities over time. Three RR Lyrae show suspicious variation in the center--of--mass velocities that may indicate binary motion but do not prove it (SS Leo, ST Leo, and AO Peg). TU UMa was observed by us near a predicted periastron passage (at 0.14 in orbital phase) but the absence of additional center--of--mass velocities near periastron make the binary detection, based on radial velocities alone, uncertain. Two stars in our sample show $H纬$ emission in phases 0.9--1.0: SS Leo and TU UMa. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.05208v1-abstract-full').style.display = 'none'; document.getElementById('2106.05208v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 June, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 tables, 21 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2103.17273">arXiv:2103.17273</a> <span> [<a href="https://arxiv.org/pdf/2103.17273">pdf</a>, <a href="https://arxiv.org/format/2103.17273">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> </div> </div> <p class="title is-5 mathjax"> Fast and Accurate Emulation of the SDO/HMI Stokes Inversion with Uncertainty Quantification </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Higgins%2C+R+E+L">Richard E. L. Higgins</a>, <a href="/search/astro-ph?searchtype=author&query=Fouhey%2C+D+F">David F. Fouhey</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+D">Dichang Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Antiochos%2C+S+K">Spiro K. Antiochos</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+G">Graham Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Hoeksema%2C+J+T">J. Todd Hoeksema</a>, <a href="/search/astro-ph?searchtype=author&query=Leka%2C+K+D">K. D. Leka</a>, <a href="/search/astro-ph?searchtype=author&query=Liu%2C+Y">Yang Liu</a>, <a href="/search/astro-ph?searchtype=author&query=Schuck%2C+P+W">Peter W. Schuck</a>, <a href="/search/astro-ph?searchtype=author&query=Gombosi%2C+T+I">Tamas I. Gombosi</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2103.17273v2-abstract-short" style="display: inline;"> The Helioseismic and Magnetic Imager (HMI) onboard NASA's Solar Dynamics Observatory (SDO) produces estimates of the photospheric magnetic field which are a critical input to many space weather modelling and forecasting systems. The magnetogram products produced by HMI and its analysis pipeline are the result of a per-pixel optimization that estimates solar atmospheric parameters and minimizes dis… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2103.17273v2-abstract-full').style.display = 'inline'; document.getElementById('2103.17273v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2103.17273v2-abstract-full" style="display: none;"> The Helioseismic and Magnetic Imager (HMI) onboard NASA's Solar Dynamics Observatory (SDO) produces estimates of the photospheric magnetic field which are a critical input to many space weather modelling and forecasting systems. The magnetogram products produced by HMI and its analysis pipeline are the result of a per-pixel optimization that estimates solar atmospheric parameters and minimizes disagreement between a synthesized and observed Stokes vector. In this paper, we introduce a deep learning-based approach that can emulate the existing HMI pipeline results two orders of magnitude faster than the current pipeline algorithms. Our system is a U-Net trained on input Stokes vectors and their accompanying optimization-based VFISV inversions. We demonstrate that our system, once trained, can produce high-fidelity estimates of the magnetic field and kinematic and thermodynamic parameters while also producing meaningful confidence intervals. We additionally show that despite penalizing only per-pixel loss terms, our system is able to faithfully reproduce known systematic oscillations in full-disk statistics produced by the pipeline. This emulation system could serve as an initialization for the full Stokes inversion or as an ultra-fast proxy inversion. This work is part of the NASA Heliophysics DRIVE Science Center (SOLSTICE) at the University of Michigan, under grant NASA 80NSSC20K0600E, and has been open sourced. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2103.17273v2-abstract-full').style.display = 'none'; document.getElementById('2103.17273v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 31 March, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2008.08863">arXiv:2008.08863</a> <span> [<a href="https://arxiv.org/pdf/2008.08863">pdf</a>, <a href="https://arxiv.org/format/2008.08863">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/aba752">10.3847/1538-4357/aba752 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> On measuring divergence for magnetic field modeling </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Gilchrist%2C+S+A">S. A. Gilchrist</a>, <a href="/search/astro-ph?searchtype=author&query=Leka%2C+K+D">K. D. Leka</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+G">G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Wheatland%2C+M+S">M. S. Wheatland</a>, <a href="/search/astro-ph?searchtype=author&query=DeRosa%2C+M+L">M. L. DeRosa</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2008.08863v1-abstract-short" style="display: inline;"> A physical magnetic field has a divergence of zero. Numerical error in constructing a model field and computing the divergence, however, introduces a finite divergence into these calculations. A popular metric for measuring divergence is the average fractional flux $\langle |f_{i}| \rangle$. We show that $\langle |f_{i}| \rangle$ scales with the size of the computational mesh, and may be a poor me… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.08863v1-abstract-full').style.display = 'inline'; document.getElementById('2008.08863v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2008.08863v1-abstract-full" style="display: none;"> A physical magnetic field has a divergence of zero. Numerical error in constructing a model field and computing the divergence, however, introduces a finite divergence into these calculations. A popular metric for measuring divergence is the average fractional flux $\langle |f_{i}| \rangle$. We show that $\langle |f_{i}| \rangle$ scales with the size of the computational mesh, and may be a poor measure of divergence because it becomes arbitrarily small for increasing mesh resolution, without the divergence actually decreasing. We define a modified version of this metric that does not scale with mesh size. We apply the new metric to the results of DeRosa et al. (2015), who measured $\langle |f_{i}| \rangle$ for a series of Nonlinear Force-Free Field (NLFFF) models of the coronal magnetic field based on solar boundary data binned at different spatial resolutions. We compute a number of divergence metrics for the DeRosa et al. (2015) data and analyze the effect of spatial resolution on these metrics using a non-parametric method. We find that some of the trends reported by DeRosa et al. (2015) are due to the intrinsic scaling of $\langle |f_{i}| \rangle$. We also find that different metrics give different results for the same data set and therefore there is value in measuring divergence via several metrics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.08863v1-abstract-full').style.display = 'none'; document.getElementById('2008.08863v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 August, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in ApJ</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ApJ 900 136 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2001.02808">arXiv:2001.02808</a> <span> [<a href="https://arxiv.org/pdf/2001.02808">pdf</a>, <a href="https://arxiv.org/format/2001.02808">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ab65f0">10.3847/1538-4357/ab65f0 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A Comparison of Flare Forecasting Methods. IV. Evaluating Consecutive-Day Forecasting Patterns </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Park%2C+S">Sung-Hong Park</a>, <a href="/search/astro-ph?searchtype=author&query=Leka%2C+K+D">K. D. Leka</a>, <a href="/search/astro-ph?searchtype=author&query=Kusano%2C+K">Kanya Kusano</a>, <a href="/search/astro-ph?searchtype=author&query=Andries%2C+J">Jesse Andries</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+G">Graham Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Bingham%2C+S">Suzy Bingham</a>, <a href="/search/astro-ph?searchtype=author&query=Bloomfield%2C+D+S">D. Shaun Bloomfield</a>, <a href="/search/astro-ph?searchtype=author&query=McCloskey%2C+A+E">Aoife E. McCloskey</a>, <a href="/search/astro-ph?searchtype=author&query=Delouille%2C+V">Veronique Delouille</a>, <a href="/search/astro-ph?searchtype=author&query=Falconer%2C+D">David Falconer</a>, <a href="/search/astro-ph?searchtype=author&query=Gallagher%2C+P+T">Peter T. Gallagher</a>, <a href="/search/astro-ph?searchtype=author&query=Georgoulis%2C+M+K">Manolis K. Georgoulis</a>, <a href="/search/astro-ph?searchtype=author&query=Kubo%2C+Y">Yuki Kubo</a>, <a href="/search/astro-ph?searchtype=author&query=Lee%2C+K">Kangjin Lee</a>, <a href="/search/astro-ph?searchtype=author&query=Lee%2C+S">Sangwoo Lee</a>, <a href="/search/astro-ph?searchtype=author&query=Lobzin%2C+V">Vasily Lobzin</a>, <a href="/search/astro-ph?searchtype=author&query=Mun%2C+J">JunChul Mun</a>, <a href="/search/astro-ph?searchtype=author&query=Murray%2C+S+A">Sophie A. Murray</a>, <a href="/search/astro-ph?searchtype=author&query=Nageem%2C+T+A+M+H">Tarek A. M. Hamad Nageem</a>, <a href="/search/astro-ph?searchtype=author&query=Qahwaji%2C+R">Rami Qahwaji</a>, <a href="/search/astro-ph?searchtype=author&query=Sharpe%2C+M">Michael Sharpe</a>, <a href="/search/astro-ph?searchtype=author&query=Steenburgh%2C+R+A">Rob A. Steenburgh</a>, <a href="/search/astro-ph?searchtype=author&query=Steward%2C+G">Graham Steward</a>, <a href="/search/astro-ph?searchtype=author&query=Terkildsen%2C+M">Michael Terkildsen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2001.02808v2-abstract-short" style="display: inline;"> A crucial challenge to successful flare prediction is forecasting periods that transition between "flare-quiet" and "flare-active". Building on earlier studies in this series (Barnes et al. 2016; Leka et al. 2019a,b) in which we describe methodology, details, and results of flare forecasting comparison efforts, we focus here on patterns of forecast outcomes (success and failure) over multi-day per… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2001.02808v2-abstract-full').style.display = 'inline'; document.getElementById('2001.02808v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2001.02808v2-abstract-full" style="display: none;"> A crucial challenge to successful flare prediction is forecasting periods that transition between "flare-quiet" and "flare-active". Building on earlier studies in this series (Barnes et al. 2016; Leka et al. 2019a,b) in which we describe methodology, details, and results of flare forecasting comparison efforts, we focus here on patterns of forecast outcomes (success and failure) over multi-day periods. A novel analysis is developed to evaluate forecasting success in the context of catching the first event of flare-active periods, and conversely, of correctly predicting declining flare activity. We demonstrate these evaluation methods graphically and quantitatively as they provide both quick comparative evaluations and options for detailed analysis. For the testing interval 2016-2017, we determine the relative frequency distribution of two-day dichotomous forecast outcomes for three different event histories (i.e., event/event, no-event/event and event/no-event), and use it to highlight performance differences between forecasting methods. A trend is identified across all forecasting methods that a high/low forecast probability on day-1 remains high/low on day-2 even though flaring activity is transitioning. For M-class and larger flares, we find that explicitly including persistence or prior flare history in computing forecasts helps to improve overall forecast performance. It is also found that using magnetic/modern data leads to improvement in catching the first-event/first-no-event transitions. Finally, 15% of major (i.e., M-class or above) flare days over the testing interval were effectively missed due to a lack of observations from instruments away from the Earth-Sun line. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2001.02808v2-abstract-full').style.display = 'none'; document.getElementById('2001.02808v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 January, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 January, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">33 pages, 13 figures, accepted for publication in ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1907.02909">arXiv:1907.02909</a> <span> [<a href="https://arxiv.org/pdf/1907.02909">pdf</a>, <a href="https://arxiv.org/ps/1907.02909">ps</a>, <a href="https://arxiv.org/format/1907.02909">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Data Analysis, Statistics and Probability">physics.data-an</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ab2e11">10.3847/1538-4357/ab2e11 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A Comparison of Flare Forecasting Methods. III. Systematic Behaviors of Operational Solar Flare Forecasting Systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Leka%2C+K+D">K. D. Leka</a>, <a href="/search/astro-ph?searchtype=author&query=Park%2C+S">Sung-Hong Park</a>, <a href="/search/astro-ph?searchtype=author&query=Kusano%2C+K">Kanya Kusano</a>, <a href="/search/astro-ph?searchtype=author&query=Andries%2C+J">Jesse Andries</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+G">Graham Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Bingham%2C+S">Suzy Bingham</a>, <a href="/search/astro-ph?searchtype=author&query=Bloomfield%2C+D+S">D. Shaun Bloomfield</a>, <a href="/search/astro-ph?searchtype=author&query=McCloskey%2C+A+E">Aoife E. McCloskey</a>, <a href="/search/astro-ph?searchtype=author&query=Delouille%2C+V">Veronique Delouille</a>, <a href="/search/astro-ph?searchtype=author&query=Falconer%2C+D">David Falconer</a>, <a href="/search/astro-ph?searchtype=author&query=Gallagher%2C+P+T">Peter T. Gallagher</a>, <a href="/search/astro-ph?searchtype=author&query=Georgoulis%2C+M+K">Manolis K. Georgoulis</a>, <a href="/search/astro-ph?searchtype=author&query=Kubo%2C+Y">Yuki Kubo</a>, <a href="/search/astro-ph?searchtype=author&query=Lee%2C+K">Kangjin Lee</a>, <a href="/search/astro-ph?searchtype=author&query=Lee%2C+S">Sangwoo Lee</a>, <a href="/search/astro-ph?searchtype=author&query=Lobzin%2C+V">Vasily Lobzin</a>, <a href="/search/astro-ph?searchtype=author&query=Mun%2C+J">JunChul Mun</a>, <a href="/search/astro-ph?searchtype=author&query=Murray%2C+S+A">Sophie A. Murray</a>, <a href="/search/astro-ph?searchtype=author&query=Nageem%2C+T+A+M+H">Tarek A. M. Hamad Nageem</a>, <a href="/search/astro-ph?searchtype=author&query=Qahwaji%2C+R">Rami Qahwaji</a>, <a href="/search/astro-ph?searchtype=author&query=Sharpe%2C+M">Michael Sharpe</a>, <a href="/search/astro-ph?searchtype=author&query=Steenburgh%2C+R">Rob Steenburgh</a>, <a href="/search/astro-ph?searchtype=author&query=Steward%2C+G">Graham Steward</a>, <a href="/search/astro-ph?searchtype=author&query=Terkildsen%2C+M">Michael Terkildsen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1907.02909v1-abstract-short" style="display: inline;"> A workshop was recently held at Nagoya University (31 October - 02 November 2017), sponsored by the Center for International Collaborative Research, at the Institute for Space-Earth Environmental Research, Nagoya University, Japan, to quantitatively compare the performance of today's operational solar flare forecasting facilities. Building upon Paper I of this series (Barnes et al. 2016), in Paper… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1907.02909v1-abstract-full').style.display = 'inline'; document.getElementById('1907.02909v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1907.02909v1-abstract-full" style="display: none;"> A workshop was recently held at Nagoya University (31 October - 02 November 2017), sponsored by the Center for International Collaborative Research, at the Institute for Space-Earth Environmental Research, Nagoya University, Japan, to quantitatively compare the performance of today's operational solar flare forecasting facilities. Building upon Paper I of this series (Barnes et al. 2016), in Paper II (Leka et al. 2019) we described the participating methods for this latest comparison effort, the evaluation methodology, and presented quantitative comparisons. In this paper we focus on the behavior and performance of the methods when evaluated in the context of broad implementation differences. Acknowledging the short testing interval available and the small number of methods available, we do find that forecast performance: 1) appears to improve by including persistence or prior flare activity, region evolution, and a human "forecaster in the loop"; 2) is hurt by restricting data to disk-center observations; 3) may benefit from long-term statistics, but mostly when then combined with modern data sources and statistical approaches. These trends are arguably weak and must be viewed with numerous caveats, as discussed both here and in Paper II. Following this present work, we present in Paper IV a novel analysis method to evaluate temporal patterns of forecasting errors of both types (i.e., misses and false alarms; Park et al. 2019). Hence, most importantly, with this series of papers we demonstrate the techniques for facilitating comparisons in the interest of establishing performance-positive methodologies. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1907.02909v1-abstract-full').style.display = 'none'; document.getElementById('1907.02909v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 July, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">23 pages, 6 figures, accepted for publication in The Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1907.02905">arXiv:1907.02905</a> <span> [<a href="https://arxiv.org/pdf/1907.02905">pdf</a>, <a href="https://arxiv.org/ps/1907.02905">ps</a>, <a href="https://arxiv.org/format/1907.02905">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Data Analysis, Statistics and Probability">physics.data-an</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ab2e12">10.3847/1538-4365/ab2e12 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A Comparison of Flare Forecasting Methods. II. Benchmarks, Metrics and Performance Results for Operational Solar Flare Forecasting Systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Leka%2C+K+D">K. D. Leka</a>, <a href="/search/astro-ph?searchtype=author&query=Park%2C+S">Sung-Hong Park</a>, <a href="/search/astro-ph?searchtype=author&query=Kusano%2C+K">Kanya Kusano</a>, <a href="/search/astro-ph?searchtype=author&query=Andries%2C+J">Jesse Andries</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+G">Graham Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Bingham%2C+S">Suzy Bingham</a>, <a href="/search/astro-ph?searchtype=author&query=Bloomfield%2C+D+S">D. Shaun Bloomfield</a>, <a href="/search/astro-ph?searchtype=author&query=McCloskey%2C+A+E">Aoife E. McCloskey</a>, <a href="/search/astro-ph?searchtype=author&query=Delouille%2C+V">Veronique Delouille</a>, <a href="/search/astro-ph?searchtype=author&query=Falconer%2C+D">David Falconer</a>, <a href="/search/astro-ph?searchtype=author&query=Gallagher%2C+P+T">Peter T. Gallagher</a>, <a href="/search/astro-ph?searchtype=author&query=Georgoulis%2C+M+K">Manolis K. Georgoulis</a>, <a href="/search/astro-ph?searchtype=author&query=Kubo%2C+Y">Yuki Kubo</a>, <a href="/search/astro-ph?searchtype=author&query=Lee%2C+K">Kangjin Lee</a>, <a href="/search/astro-ph?searchtype=author&query=Lee%2C+S">Sangwoo Lee</a>, <a href="/search/astro-ph?searchtype=author&query=Lobzin%2C+V">Vasily Lobzin</a>, <a href="/search/astro-ph?searchtype=author&query=Mun%2C+J">JunChul Mun</a>, <a href="/search/astro-ph?searchtype=author&query=Murray%2C+S+A">Sophie A. Murray</a>, <a href="/search/astro-ph?searchtype=author&query=Nageem%2C+T+A+M+H">Tarek A. M. Hamad Nageem</a>, <a href="/search/astro-ph?searchtype=author&query=Qahwaji%2C+R">Rami Qahwaji</a>, <a href="/search/astro-ph?searchtype=author&query=Sharpe%2C+M">Michael Sharpe</a>, <a href="/search/astro-ph?searchtype=author&query=Steenburgh%2C+R">Rob Steenburgh</a>, <a href="/search/astro-ph?searchtype=author&query=Steward%2C+G">Graham Steward</a>, <a href="/search/astro-ph?searchtype=author&query=Terkildsen%2C+M">Michael Terkildsen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1907.02905v1-abstract-short" style="display: inline;"> Solar flares are extremely energetic phenomena in our Solar System. Their impulsive, often drastic radiative increases, in particular at short wavelengths, bring immediate impacts that motivate solar physics and space weather research to understand solar flares to the point of being able to forecast them. As data and algorithms improve dramatically, questions must be asked concerning how well the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1907.02905v1-abstract-full').style.display = 'inline'; document.getElementById('1907.02905v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1907.02905v1-abstract-full" style="display: none;"> Solar flares are extremely energetic phenomena in our Solar System. Their impulsive, often drastic radiative increases, in particular at short wavelengths, bring immediate impacts that motivate solar physics and space weather research to understand solar flares to the point of being able to forecast them. As data and algorithms improve dramatically, questions must be asked concerning how well the forecasting performs; crucially, we must ask how to rigorously measure performance in order to critically gauge any improvements. Building upon earlier-developed methodology (Barnes et al, 2016, Paper I), international representatives of regional warning centers and research facilities assembled in 2017 at the Institute for Space-Earth Environmental Research, Nagoya University, Japan to - for the first time - directly compare the performance of operational solar flare forecasting methods. Multiple quantitative evaluation metrics are employed, with focus and discussion on evaluation methodologies given the restrictions of operational forecasting. Numerous methods performed consistently above the "no skill" level, although which method scored top marks is decisively a function of flare event definition and the metric used; there was no single winner. Following in this paper series we ask why the performances differ by examining implementation details (Leka et al. 2019, Paper III), and then we present a novel analysis method to evaluate temporal patterns of forecasting errors in (Park et al. 2019, Paper IV). With these works, this team presents a well-defined and robust methodology for evaluating solar flare forecasting methods in both research and operational frameworks, and today's performance benchmarks against which improvements and new methods may be compared. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1907.02905v1-abstract-full').style.display = 'none'; document.getElementById('1907.02905v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 July, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">26 pages, 5 figures, accepted for publication in the Astrophysical Journal Supplement Series</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1809.04073">arXiv:1809.04073</a> <span> [<a href="https://arxiv.org/pdf/1809.04073">pdf</a>, <a href="https://arxiv.org/ps/1809.04073">ps</a>, <a href="https://arxiv.org/format/1809.04073">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/201833263">10.1051/0004-6361/201833263 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The effect of metallicity on Cepheid Period-Luminosity relations from a Baade-Wesselink analysis of Cepheids in the Milky Way and Magellanic Clouds </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Gieren%2C+W">W. Gieren</a>, <a href="/search/astro-ph?searchtype=author&query=Storm%2C+J">J. Storm</a>, <a href="/search/astro-ph?searchtype=author&query=Konorski%2C+P">P. Konorski</a>, <a href="/search/astro-ph?searchtype=author&query=G%C3%B3rski%2C+M">M. G贸rski</a>, <a href="/search/astro-ph?searchtype=author&query=Pilecki%2C+B">B. Pilecki</a>, <a href="/search/astro-ph?searchtype=author&query=Thompson%2C+I">I. Thompson</a>, <a href="/search/astro-ph?searchtype=author&query=Pietrzy%C5%84ski%2C+G">G. Pietrzy艅ski</a>, <a href="/search/astro-ph?searchtype=author&query=Graczyk%2C+D">D. Graczyk</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+T+G">T. G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Fouqu%C3%A9%2C+P">P. Fouqu茅</a>, <a href="/search/astro-ph?searchtype=author&query=Nardetto%2C+N">N. Nardetto</a>, <a href="/search/astro-ph?searchtype=author&query=Gallenne%2C+A">A. Gallenne</a>, <a href="/search/astro-ph?searchtype=author&query=Karczmarek%2C+P">P. Karczmarek</a>, <a href="/search/astro-ph?searchtype=author&query=Suchomska%2C+K">K. Suchomska</a>, <a href="/search/astro-ph?searchtype=author&query=Wielg%C3%B3rski%2C+P">P. Wielg贸rski</a>, <a href="/search/astro-ph?searchtype=author&query=Taormina%2C+M">M. Taormina</a>, <a href="/search/astro-ph?searchtype=author&query=Zgirski%2C+B">B. Zgirski</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1809.04073v1-abstract-short" style="display: inline;"> The extragalactic distance scale builds on the Cepheid period-luminosity (PL) relation. In this paper, we want to carry out a strictly differential comparison of the absolute PL relations obeyed by classical Cepheids in the Milky Way (MW), LMC and SMC galaxies. Taking advantage of the substantial metallicity difference among the Cepheid populations in these three galaxies, we want to establish a p… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1809.04073v1-abstract-full').style.display = 'inline'; document.getElementById('1809.04073v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1809.04073v1-abstract-full" style="display: none;"> The extragalactic distance scale builds on the Cepheid period-luminosity (PL) relation. In this paper, we want to carry out a strictly differential comparison of the absolute PL relations obeyed by classical Cepheids in the Milky Way (MW), LMC and SMC galaxies. Taking advantage of the substantial metallicity difference among the Cepheid populations in these three galaxies, we want to establish a possible systematic trend of the PL relation absolute zero point as a function of metallicity, and determine the size of such an effect in optical and near-infrared photometric bands. We are using the IRSB Baade-Wesselink type method as calibrated by Storm et al. to determine individual distances to the Cepheids in our samples in MW, LMC and SMC. For our analysis, we use a greatly enhanced sample of Cepheids in the SMC (31 stars) as compared to the small sample (5 stars) available in our previous work. We use the distances to determine absolute Cepheid PL relations in optical and near-infrared bands in each of the three galaxies.} {Our distance analysis of 31 SMC Cepheids with periods from 4-69 days yields tight PL relations in all studied bands, with slopes consistent with the corresponding LMC and MW relations. Adopting the very accurately determined LMC slopes for the optical and near-infrared bands, we determine the zero point offsets between the corresponding absolute PL relations in the 3 galaxies. We find that in all bands the metal-poor SMC Cepheids are intrinsically fainter than their more metal-rich counterparts in the LMC and MW. In the $K$ band the metallicity effect is $-0.23\pm0.06$~mag/dex while in the $V,(V-I)$ Wesenheit index it is slightly stronger, $-0.34\pm0.06$~mag/dex. We find some evidence that the PL relation zero point-metallicity relation might be nonlinear, becoming steeper for lower metallicities. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1809.04073v1-abstract-full').style.display = 'none'; document.getElementById('1809.04073v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 September, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">20 pages, accepted for publication by A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 620, A99 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1805.03354">arXiv:1805.03354</a> <span> [<a href="https://arxiv.org/pdf/1805.03354">pdf</a>, <a href="https://arxiv.org/format/1805.03354">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Cosmology and Nongalactic Astrophysics">astro-ph.CO</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1017/pasa.2018.19">10.1017/pasa.2018.19 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Immersive Virtual Reality Experiences for All-Sky Data </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Fluke%2C+C+J">C. J. Fluke</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+D+G">D. G. Barnes</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1805.03354v1-abstract-short" style="display: inline;"> Spherical coordinate systems, which are ubiquitous in astronomy, cannot be shown without distortion on flat, two-dimensional surfaces. This poses challenges for the two complementary phases of visual exploration -- making discoveries in data by looking for relationships, patterns or anomalies -- and publication -- where the results of an exploration are made available for scientific scrutiny or co… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1805.03354v1-abstract-full').style.display = 'inline'; document.getElementById('1805.03354v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1805.03354v1-abstract-full" style="display: none;"> Spherical coordinate systems, which are ubiquitous in astronomy, cannot be shown without distortion on flat, two-dimensional surfaces. This poses challenges for the two complementary phases of visual exploration -- making discoveries in data by looking for relationships, patterns or anomalies -- and publication -- where the results of an exploration are made available for scientific scrutiny or communication. This is a long-standing problem, and many practical solutions have been developed. Our allskyVR approach provides a workflow for experimentation with commodity virtual reality head-mounted displays. Using the free, open source S2PLOT programming library, and the A-Frame WebVR browser-based framework, we provide a straightforward way to visualise all-sky catalogues on a user-centred, virtual celestial sphere. The allskyVR distribution contains both a quickstart option, complete with a gaze-based menu system, and a fully customisable mode for those who need more control of the immersive experience. The software is available for download from: https://github.com/cfluke/allskyVR <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1805.03354v1-abstract-full').style.display = 'none'; document.getElementById('1805.03354v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 May, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 3 figures, accepted for publication in Publications of the Astronomical Society of Australia</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1802.06864">arXiv:1802.06864</a> <span> [<a href="https://arxiv.org/pdf/1802.06864">pdf</a>, <a href="https://arxiv.org/ps/1802.06864">ps</a>, <a href="https://arxiv.org/format/1802.06864">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Data Analysis, Statistics and Probability">physics.data-an</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> </div> <p class="title is-5 mathjax"> The NWRA Classification Infrastructure: Description and Extension to the Discriminant Analysis Flare Forecasting System (DAFFS) </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Leka%2C+K+D">K. D. Leka</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+G">Graham Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Wagner%2C+E+L">Eric L. Wagner</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1802.06864v1-abstract-short" style="display: inline;"> A classification infrastructure built upon Discriminant Analysis has been developed at NorthWest Research Associates for examining the statistical differences between samples of two known populations. Originating to examine the physical differences between flare-quiet and flare-imminent solar active regions, we describe herein some details of the infrastructure including: parametrization of large… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1802.06864v1-abstract-full').style.display = 'inline'; document.getElementById('1802.06864v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1802.06864v1-abstract-full" style="display: none;"> A classification infrastructure built upon Discriminant Analysis has been developed at NorthWest Research Associates for examining the statistical differences between samples of two known populations. Originating to examine the physical differences between flare-quiet and flare-imminent solar active regions, we describe herein some details of the infrastructure including: parametrization of large datasets, schemes for handling "null" and "bad" data in multi-parameter analysis, application of non-parametric multi-dimensional Discriminant Analysis, an extension through Bayes' theorem to probabilistic classification, and methods invoked for evaluating classifier success. The classifier infrastructure is applicable to a wide range of scientific questions in solar physics. We demonstrate its application to the question of distinguishing flare-imminent from flare-quiet solar active regions, updating results from the original publications that were based on different data and much smaller sample sizes. Finally, as a demonstration of "Research to Operations" efforts in the space-weather forecasting context, we present the Discriminant Analysis Flare Forecasting System (DAFFS), a near-real-time operationally-running solar flare forecasting tool that was developed from the research-directed infrastructure. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1802.06864v1-abstract-full').style.display = 'none'; document.getElementById('1802.06864v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 February, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">J. Space Weather Space Climate: Accepted / in press; access supplementary materials through journal; some figures are less than full resolution for arXiv</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1802.01199">arXiv:1802.01199</a> <span> [<a href="https://arxiv.org/pdf/1802.01199">pdf</a>, <a href="https://arxiv.org/format/1802.01199">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/aac77a">10.3847/1538-4357/aac77a <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Does Nearby Open Flux Affect the Eruptivity of Solar Active Regions? </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=DeRosa%2C+M+L">Marc L. DeRosa</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+G">Graham Barnes</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1802.01199v2-abstract-short" style="display: inline;"> The most energetic solar flares are typically associated with the ejection of a cloud of coronal material into the heliosphere in the form of a coronal mass ejection (CME). However, there exist large flares which are not accompanied by a CME. The existence of these non-eruptive flares raises the question of whether such flares suffer from a lack of access to nearby open fields in the vicinity abov… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1802.01199v2-abstract-full').style.display = 'inline'; document.getElementById('1802.01199v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1802.01199v2-abstract-full" style="display: none;"> The most energetic solar flares are typically associated with the ejection of a cloud of coronal material into the heliosphere in the form of a coronal mass ejection (CME). However, there exist large flares which are not accompanied by a CME. The existence of these non-eruptive flares raises the question of whether such flares suffer from a lack of access to nearby open fields in the vicinity above the flare (reconnection) site. In this study, we use a sample of 56 flares from Sunspot Cycles 23 and 24 to test whether active regions that produce eruptive X-class flares are preferentially located near coronal magnetic field domains that are open to the heliosphere, as inferred from a potential field source surface model. The study shows that X-class flares having access to open fields are eruptive at a higher rate than those for which access is lacking. The significance of this result should be moderated due to the small number of non-eruptive X-class flares in the sample, based on the associated Bayes factor. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1802.01199v2-abstract-full').style.display = 'none'; document.getElementById('1802.01199v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 May, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 4 February, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">ApJ accepted</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1710.06709">arXiv:1710.06709</a> <span> [<a href="https://arxiv.org/pdf/1710.06709">pdf</a>, <a href="https://arxiv.org/ps/1710.06709">ps</a>, <a href="https://arxiv.org/format/1710.06709">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/stx2737">10.1093/mnras/stx2737 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A cautionary tale of interpreting O-C diagrams: period instability in a classical RR Lyr Star Z CVn mimicking as a distant companion </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Skarka%2C+M">M. Skarka</a>, <a href="/search/astro-ph?searchtype=author&query=Li%C5%A1ka%2C+J">J. Li拧ka</a>, <a href="/search/astro-ph?searchtype=author&query=D%C5%99ev%C4%9Bn%C3%BD%2C+R">R. D艡ev臎n媒</a>, <a href="/search/astro-ph?searchtype=author&query=Guggenberger%2C+E">E. Guggenberger</a>, <a href="/search/astro-ph?searchtype=author&query=S%C3%B3dor%2C+%C3%81">脕. S贸dor</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+T+G">T. G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Kolenberg%2C+K">K. Kolenberg</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1710.06709v1-abstract-short" style="display: inline;"> We present a comprehensive study of Z CVn, an RR Lyrae star that shows long-term cyclic variations of its pulsation period. A possible explanation suggested from the shape of the O-C diagram is the light travel-time effect, which we thoroughly examine. We used original photometric and spectroscopic measurements and investigated the period evolution using available maximum times spanning more than… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1710.06709v1-abstract-full').style.display = 'inline'; document.getElementById('1710.06709v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1710.06709v1-abstract-full" style="display: none;"> We present a comprehensive study of Z CVn, an RR Lyrae star that shows long-term cyclic variations of its pulsation period. A possible explanation suggested from the shape of the O-C diagram is the light travel-time effect, which we thoroughly examine. We used original photometric and spectroscopic measurements and investigated the period evolution using available maximum times spanning more than one century. If the binary hypothesis is valid, Z CVn orbits around a black hole with minimal mass of $56.5$ $\mathfrak{M}_{\odot}$ on a very wide ($P_{\rm orbit}=78.3$ years) and eccentric orbit ($e=0.63$). We discuss the probability of a formation of a black hole-RR Lyrae pair and, although we found it possible, there is no observational evidence of the black hole in the direction to Z CVn. However, the main objection against the binary hypothesis is the comparison of the systemic radial velocity curve model and spectroscopic observations that clearly show that Z CVn cannot be bound in such a binary. Therefore, the variations of pulsation period are likely intrinsic to the star. This finding represents a discovery/confirmation of a new type of cyclic period changes in RR Lyrae stars. By the analysis of our photometric data, we found that the Blazhko modulation with period of 22.931 d is strongly dominant in amplitude. The strength of the phase modulation varies and is currently almost undetectable. We also estimated photometric physical parameters of Z CVn and investigated their variations during the Blazhko cycle using the Inverse Baade-Wesselink method. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1710.06709v1-abstract-full').style.display = 'none'; document.getElementById('1710.06709v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 October, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">15 pages, 8 tables, 9 figures, accepted for publication in MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1707.00442">arXiv:1707.00442</a> <span> [<a href="https://arxiv.org/pdf/1707.00442">pdf</a>, <a href="https://arxiv.org/format/1707.00442">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/stx1676">10.1093/mnras/stx1676 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Real-time colouring and filtering with graphics shaders </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Vohl%2C+D">Dany Vohl</a>, <a href="/search/astro-ph?searchtype=author&query=Fluke%2C+C+J">Christopher J. Fluke</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+D+G">David G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Hassan%2C+A+H">Amr H. Hassan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1707.00442v1-abstract-short" style="display: inline;"> Despite the popularity of the Graphics Processing Unit (GPU) for general purpose computing, one should not forget about the practicality of the GPU for fast scientific visualisation. As astronomers have increasing access to three dimensional (3D) data from instruments and facilities like integral field units and radio interferometers, visualisation techniques such as volume rendering offer means t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1707.00442v1-abstract-full').style.display = 'inline'; document.getElementById('1707.00442v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1707.00442v1-abstract-full" style="display: none;"> Despite the popularity of the Graphics Processing Unit (GPU) for general purpose computing, one should not forget about the practicality of the GPU for fast scientific visualisation. As astronomers have increasing access to three dimensional (3D) data from instruments and facilities like integral field units and radio interferometers, visualisation techniques such as volume rendering offer means to quickly explore spectral cubes as a whole. As most 3D visualisation techniques have been developed in fields of research like medical imaging and fluid dynamics, many transfer functions are not optimal for astronomical data. We demonstrate how transfer functions and graphics shaders can be exploited to provide new astronomy-specific explorative colouring methods. We present 12 shaders, including four novel transfer functions specifically designed to produce intuitive and informative 3D visualisations of spectral cube data. We compare their utility to classic colour mapping. The remaining shaders highlight how common computation like filtering, smoothing and line ratio algorithms can be integrated as part of the graphics pipeline. We discuss how this can be achieved by utilising the parallelism of modern GPUs along with a shading language, letting astronomers apply these new techniques at interactive frame rates. All shaders investigated in this work are included in the open source software shwirl (Vohl, 2017). <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1707.00442v1-abstract-full').style.display = 'none'; document.getElementById('1707.00442v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 July, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">24 pages, 19 figures, 14 algorithms, 1 table. Accepted for publication by Monthly Notices of the Royal Astronomical Society</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1703.06456">arXiv:1703.06456</a> <span> [<a href="https://arxiv.org/pdf/1703.06456">pdf</a>, <a href="https://arxiv.org/format/1703.06456">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/201630327">10.1051/0004-6361/201630327 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A comprehensive study of young B stars in NGC 2264: I. Space photometry and asteroseismology </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Zwintz%2C+K">K. Zwintz</a>, <a href="/search/astro-ph?searchtype=author&query=Moravveji%2C+E">E. Moravveji</a>, <a href="/search/astro-ph?searchtype=author&query=Papics%2C+P+I">P. I. Papics</a>, <a href="/search/astro-ph?searchtype=author&query=Tkachenko%2C+A">A. Tkachenko</a>, <a href="/search/astro-ph?searchtype=author&query=Przybilla%2C+N">N. Przybilla</a>, <a href="/search/astro-ph?searchtype=author&query=Nieva%2C+M+-">M. -F. Nieva</a>, <a href="/search/astro-ph?searchtype=author&query=Kuschnig%2C+R">R. Kuschnig</a>, <a href="/search/astro-ph?searchtype=author&query=Antoci%2C+V">V. Antoci</a>, <a href="/search/astro-ph?searchtype=author&query=Lorenz%2C+D">D. Lorenz</a>, <a href="/search/astro-ph?searchtype=author&query=Themessl%2C+N">N. Themessl</a>, <a href="/search/astro-ph?searchtype=author&query=Fossati%2C+L">L. Fossati</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+T+G">T. G. Barnes</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1703.06456v1-abstract-short" style="display: inline;"> Space photometric time series of the most massive members of the young open cluster NGC 2264 allow us to study their different sources of variability down to the millimagnitude level and permits a search for Slowly Pulsating B (SPB) type pulsation among objects that are only a few million years old. Our goal is to conduct a homogeneous study of young B type stars in the cluster NGC 2264 using phot… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1703.06456v1-abstract-full').style.display = 'inline'; document.getElementById('1703.06456v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1703.06456v1-abstract-full" style="display: none;"> Space photometric time series of the most massive members of the young open cluster NGC 2264 allow us to study their different sources of variability down to the millimagnitude level and permits a search for Slowly Pulsating B (SPB) type pulsation among objects that are only a few million years old. Our goal is to conduct a homogeneous study of young B type stars in the cluster NGC 2264 using photometric time series from space in combination with high-resolution spectroscopy and spectropolarimetry obtained from the ground. The latter will be presented in a separate follow-up article. We performed frequency analyses for eleven B stars in the field of the young cluster NGC 2264 using photometric time series from the MOST, CoRoT and Spitzer space telescopes and the routines Period04 and SigSpec. We employ the MESA stellar evolution code in combination with the oscillation code GYRE to identify the pulsation modes for two SPB stars which exhibit short period spacing series. From our analysis we identify four objects that show SPB pulsations, five stars that show rotational modulation of their light curves caused by spots, one star that is identified to be a binary, and one object in the field of the cluster that is found to be a non-member Be star. In two SPB stars we detect a number of regularly spaced pulsation modes that are compatible with being members of a g mode period series. Despite NGC 2264's young age, our analysis illustrates that its B type members have already arrived on the zero-age main sequence (ZAMS). Our asteroseismic analysis yields masses between 4 and 6 Msun and ages between 1 and 6 million years, which agree well to the overall cluster age. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1703.06456v1-abstract-full').style.display = 'none'; document.getElementById('1703.06456v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 March, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 20 figures, accepted for publication in Astronomy & Astrophysics</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 601, A101 (2017) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1701.04836">arXiv:1701.04836</a> <span> [<a href="https://arxiv.org/pdf/1701.04836">pdf</a>, <a href="https://arxiv.org/ps/1701.04836">ps</a>, <a href="https://arxiv.org/format/1701.04836">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1007/s11207-017-1057-8">10.1007/s11207-017-1057-8 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Evaluating (and Improving) Estimates of the Solar Radial Magnetic Field Component from Line-of-Sight Magnetograms </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Leka%2C+K+D">K. D. Leka</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+G">G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Wagner%2C+E+L">E. L. Wagner</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1701.04836v1-abstract-short" style="display: inline;"> Although for many solar physics problems the desirable or meaningful boundary is the radial component of the magnetic field $B_{\rm r}$, the most readily available measurement is the component of the magnetic field along the line-of-sight to the observer, $B_{\rm los}$. As this component is only equal to the radial component where the viewing angle is exactly zero, some approximation is required t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1701.04836v1-abstract-full').style.display = 'inline'; document.getElementById('1701.04836v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1701.04836v1-abstract-full" style="display: none;"> Although for many solar physics problems the desirable or meaningful boundary is the radial component of the magnetic field $B_{\rm r}$, the most readily available measurement is the component of the magnetic field along the line-of-sight to the observer, $B_{\rm los}$. As this component is only equal to the radial component where the viewing angle is exactly zero, some approximation is required to estimate $B_{\rm r}$ at all other observed locations. In this study, a common approximation known as the "$渭$-correction", which assumes all photospheric field to be radial, is compared to a method which invokes computing a potential field that matches the observed $B_{\rm los}$, from which the potential field radial component, $B_{\rm r}^{\rm pot}$ is recovered. We demonstrate that in regions that are truly dominated by radially-oriented field at the resolution of the data employed, the $渭$-correction performs acceptably if not better than the potential-field approach. However, it is also shown that for any solar structure which includes horizontal fields, i.e. active regions, the potential-field method better recovers both the strength of the radial field and the location of magnetic neutral line. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1701.04836v1-abstract-full').style.display = 'none'; document.getElementById('1701.04836v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 January, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in Solar Physics</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1612.00920">arXiv:1612.00920</a> <span> [<a href="https://arxiv.org/pdf/1612.00920">pdf</a>, <a href="https://arxiv.org/format/1612.00920">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1017/S1743921317001399">10.1017/S1743921317001399 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Collaborative visual analytics of radio surveys in the Big Data era </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Vohl%2C+D">Dany Vohl</a>, <a href="/search/astro-ph?searchtype=author&query=Fluke%2C+C+J">Christopher J. Fluke</a>, <a href="/search/astro-ph?searchtype=author&query=Hassan%2C+A+H">Amr H. Hassan</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+D+G">David G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Kilborn%2C+V+A">Virginia A. Kilborn</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1612.00920v1-abstract-short" style="display: inline;"> Radio survey datasets comprise an increasing number of individual observations stored as sets of multidimensional data. In large survey projects, astronomers commonly face limitations regarding: 1) interactive visual analytics of sufficiently large subsets of data; 2) synchronous and asynchronous collaboration; and 3) documentation of the discovery workflow. To support collaborative data inquiry,… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1612.00920v1-abstract-full').style.display = 'inline'; document.getElementById('1612.00920v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1612.00920v1-abstract-full" style="display: none;"> Radio survey datasets comprise an increasing number of individual observations stored as sets of multidimensional data. In large survey projects, astronomers commonly face limitations regarding: 1) interactive visual analytics of sufficiently large subsets of data; 2) synchronous and asynchronous collaboration; and 3) documentation of the discovery workflow. To support collaborative data inquiry, we present encube, a large-scale comparative visual analytics framework. Encube can utilise advanced visualization environments such as the CAVE2 (a hybrid 2D and 3D virtual reality environment powered with a 100 Tflop/s GPU-based supercomputer and 84 million pixels) for collaborative analysis of large subsets of data from radio surveys. It can also run on standard desktops, providing a capable visual analytics experience across the display ecology. Encube is composed of four primary units enabling compute-intensive processing, advanced visualisation, dynamic interaction, parallel data query, along with data management. Its modularity will make it simple to incorporate astronomical analysis packages and Virtual Observatory capabilities developed within our community. We discuss how encube builds a bridge between high-end display systems (such as CAVE2) and the classical desktop, preserving all traces of the work completed on either platform -- allowing the research process to continue wherever you are. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1612.00920v1-abstract-full').style.display = 'none'; document.getElementById('1612.00920v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 December, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for Proceedings of IAU Symposium 325</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1610.00806">arXiv:1610.00806</a> <span> [<a href="https://arxiv.org/pdf/1610.00806">pdf</a>, <a href="https://arxiv.org/format/1610.00806">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> </div> <p class="title is-5 mathjax"> An interactive, comparative and quantitative 3D visualization system for large-scale spectral-cube surveys using CAVE2 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Vohl%2C+D">Dany Vohl</a>, <a href="/search/astro-ph?searchtype=author&query=Fluke%2C+C+J">Christopher J. Fluke</a>, <a href="/search/astro-ph?searchtype=author&query=Hassan%2C+A+H">Amr H. Hassan</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+D+G">David G. Barnes</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1610.00806v1-abstract-short" style="display: inline;"> As the quantity and resolution of spectral-cubes from optical/infrared and radio surveys increase, desktop-based visualization and analysis solutions must adapt and evolve. Novel immersive 3D environments such as the CAVE2 at Monash University can overcome personal computer's visualization limitations. CAVE2 is part advanced 2D/3D visualization space (80 stereo-capable screens providing a total of… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1610.00806v1-abstract-full').style.display = 'inline'; document.getElementById('1610.00806v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1610.00806v1-abstract-full" style="display: none;"> As the quantity and resolution of spectral-cubes from optical/infrared and radio surveys increase, desktop-based visualization and analysis solutions must adapt and evolve. Novel immersive 3D environments such as the CAVE2 at Monash University can overcome personal computer's visualization limitations. CAVE2 is part advanced 2D/3D visualization space (80 stereo-capable screens providing a total of 84 million pixels) and part supercomputer ($\sim100$ TFLOPS of integrated GPU-based processing power). We present a novel visualization system enabling simultaneous 3D comparative visualization of $\sim100$ spectral-cubes. With CAVE2 augmented by our newly developed web-based controller interface, astronomers can easily organise spectral-cubes on the different display panels, apply real-time transforms to one or many spectral cubes, and request quantitative information about the displayed data. We also discuss how such a solution can help accelerate the discovery rate in varied research scenarios. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1610.00806v1-abstract-full').style.display = 'none'; document.getElementById('1610.00806v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 October, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">4 pages, 2 figures, to appear in Proceedings of ADASS XXV (Sydney, Australia; 2015), edited by N. P. F. Lorente & K. Shortridge (San Francisco: ASP), ASP Conf. Series</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1610.00760">arXiv:1610.00760</a> <span> [<a href="https://arxiv.org/pdf/1610.00760">pdf</a>, <a href="https://arxiv.org/format/1610.00760">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Human-Computer Interaction">cs.HC</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.7717/peerj-cs.88">10.7717/peerj-cs.88 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Large-scale comparative visualisation of sets of multidimensional data </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Vohl%2C+D">Dany Vohl</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+D+G">David G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Fluke%2C+C+J">Christopher J. Fluke</a>, <a href="/search/astro-ph?searchtype=author&query=Poudel%2C+G">Govinda Poudel</a>, <a href="/search/astro-ph?searchtype=author&query=Georgiou-Karistianis%2C+N">Nellie Georgiou-Karistianis</a>, <a href="/search/astro-ph?searchtype=author&query=Hassan%2C+A+H">Amr H. Hassan</a>, <a href="/search/astro-ph?searchtype=author&query=Benovitski%2C+Y">Yuri Benovitski</a>, <a href="/search/astro-ph?searchtype=author&query=Wong%2C+T+H">Tsz Ho Wong</a>, <a href="/search/astro-ph?searchtype=author&query=Kaluza%2C+O">Owen Kaluza</a>, <a href="/search/astro-ph?searchtype=author&query=Nguyen%2C+T+D">Toan D. Nguyen</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnington%2C+C+P">C. Paul Bonnington</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1610.00760v1-abstract-short" style="display: inline;"> We present encube $-$ a qualitative, quantitative and comparative visualisation and analysis system, with application to high-resolution, immersive three-dimensional environments and desktop displays. encube extends previous comparative visualisation systems by considering: 1) the integration of comparative visualisation and analysis into a unified system; 2) the documentation of the discovery pro… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1610.00760v1-abstract-full').style.display = 'inline'; document.getElementById('1610.00760v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1610.00760v1-abstract-full" style="display: none;"> We present encube $-$ a qualitative, quantitative and comparative visualisation and analysis system, with application to high-resolution, immersive three-dimensional environments and desktop displays. encube extends previous comparative visualisation systems by considering: 1) the integration of comparative visualisation and analysis into a unified system; 2) the documentation of the discovery process; and 3) an approach that enables scientists to continue the research process once back at their desktop. Our solution enables tablets, smartphones or laptops to be used as interaction units for manipulating, organising, and querying data. We highlight the modularity of encube, allowing additional functionalities to be included as required. Additionally, our approach supports a high level of collaboration within the physical environment. We show how our implementation of encube operates in a large-scale, hybrid visualisation and supercomputing environment using the CAVE2 at Monash University, and on a local desktop, making it a versatile solution. We discuss how our approach can help accelerate the discovery rate in a variety of research scenarios. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1610.00760v1-abstract-full').style.display = 'none'; document.getElementById('1610.00760v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 October, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">26 pages, 11 figures, 5 tables. Accepted for publication in PeerJ Computer Science</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1609.00733">arXiv:1609.00733</a> <span> [<a href="https://arxiv.org/pdf/1609.00733">pdf</a>, <a href="https://arxiv.org/format/1609.00733">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1007/s11207-016-0992-0">10.1007/s11207-016-0992-0 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A Fixed-point Scheme for the Numerical Construction of Magnetohydrostatic Atmospheres in Three Dimensions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Gilchrist%2C+S+A">S. A. Gilchrist</a>, <a href="/search/astro-ph?searchtype=author&query=Braun%2C+D+C">D. C. Braun</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+G">G. Barnes</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1609.00733v3-abstract-short" style="display: inline;"> Magnetohydrostatic models of the solar atmosphere are often based on idealized analytic solutions because the underlying equations are too difficult to solve in full generality. Numerical approaches, too, are often limited in scope and have tended to focus on the two-dimensional problem. In this article we develop a numerical method for solving the nonlinear magnetohydrostatic equations in three d… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1609.00733v3-abstract-full').style.display = 'inline'; document.getElementById('1609.00733v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1609.00733v3-abstract-full" style="display: none;"> Magnetohydrostatic models of the solar atmosphere are often based on idealized analytic solutions because the underlying equations are too difficult to solve in full generality. Numerical approaches, too, are often limited in scope and have tended to focus on the two-dimensional problem. In this article we develop a numerical method for solving the nonlinear magnetohydrostatic equations in three dimensions. Our method is a fixed-point iteration scheme that extends the method of Grad and Rubin (Proc. 2nd Int. Conf. on Peaceful Uses of Atomic Energy 31, 190, 1958) to include a finite gravity force. We apply the method to a test case to demonstrate the method in general and our implementation in code in particular. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1609.00733v3-abstract-full').style.display = 'none'; document.getElementById('1609.00733v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 October, 2016; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 2 September, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in Solar Physics</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1608.06319">arXiv:1608.06319</a> <span> [<a href="https://arxiv.org/pdf/1608.06319">pdf</a>, <a href="https://arxiv.org/ps/1608.06319">ps</a>, <a href="https://arxiv.org/format/1608.06319">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/0004-637X/829/2/89">10.3847/0004-637X/829/2/89 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A Comparison of Flare Forecasting Methods, I: Results from the "All-Clear" Workshop </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+G">G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Leka%2C+K+D">K. D. Leka</a>, <a href="/search/astro-ph?searchtype=author&query=Schrijver%2C+C+J">C. J. Schrijver</a>, <a href="/search/astro-ph?searchtype=author&query=Colak%2C+T">T. Colak</a>, <a href="/search/astro-ph?searchtype=author&query=Qahwaji%2C+R">R. Qahwaji</a>, <a href="/search/astro-ph?searchtype=author&query=Ashamari%2C+O+W">O. W. Ashamari</a>, <a href="/search/astro-ph?searchtype=author&query=Yuan%2C+Y">Y. Yuan</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+J">J. Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=McAteer%2C+R+T+J">R. T. J. McAteer</a>, <a href="/search/astro-ph?searchtype=author&query=Bloomfield%2C+D+S">D. S. Bloomfield</a>, <a href="/search/astro-ph?searchtype=author&query=Higgins%2C+P+A">P. A. Higgins</a>, <a href="/search/astro-ph?searchtype=author&query=Gallagher%2C+P+T">P. T. Gallagher</a>, <a href="/search/astro-ph?searchtype=author&query=Falconer%2C+D+A">D. A. Falconer</a>, <a href="/search/astro-ph?searchtype=author&query=Georgoulis%2C+M+K">M. K. Georgoulis</a>, <a href="/search/astro-ph?searchtype=author&query=Wheatland%2C+M+S">M. S. Wheatland</a>, <a href="/search/astro-ph?searchtype=author&query=Balch%2C+C">C. Balch</a>, <a href="/search/astro-ph?searchtype=author&query=Dunn%2C+T">T. Dunn</a>, <a href="/search/astro-ph?searchtype=author&query=Wagner%2C+E+L">E. L. Wagner</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1608.06319v1-abstract-short" style="display: inline;"> Solar flares produce radiation which can have an almost immediate effect on the near-Earth environment, making it crucial to forecast flares in order to mitigate their negative effects. The number of published approaches to flare forecasting using photospheric magnetic field observations has proliferated, with varying claims about how well each works. Because of the different analysis techniques a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1608.06319v1-abstract-full').style.display = 'inline'; document.getElementById('1608.06319v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1608.06319v1-abstract-full" style="display: none;"> Solar flares produce radiation which can have an almost immediate effect on the near-Earth environment, making it crucial to forecast flares in order to mitigate their negative effects. The number of published approaches to flare forecasting using photospheric magnetic field observations has proliferated, with varying claims about how well each works. Because of the different analysis techniques and data sets used, it is essentially impossible to compare the results from the literature. This problem is exacerbated by the low event rates of large solar flares. The challenges of forecasting rare events have long been recognized in the meteorology community, but have yet to be fully acknowledged by the space weather community. During the interagency workshop on "all clear" forecasts held in Boulder, CO in 2009, the performance of a number of existing algorithms was compared on common data sets, specifically line-of-sight magnetic field and continuum intensity images from MDI, with consistent definitions of what constitutes an event. We demonstrate the importance of making such systematic comparisons, and of using standard verification statistics to determine what constitutes a good prediction scheme. When a comparison was made in this fashion, no one method clearly outperformed all others, which may in part be due to the strong correlations among the parameters used by different methods to characterize an active region. For M-class flares and above, the set of methods tends towards a weakly positive skill score (as measured with several distinct metrics), with no participating method proving substantially better than climatological forecasts. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1608.06319v1-abstract-full').style.display = 'none'; document.getElementById('1608.06319v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 August, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1601.03459">arXiv:1601.03459</a> <span> [<a href="https://arxiv.org/pdf/1601.03459">pdf</a>, <a href="https://arxiv.org/ps/1601.03459">ps</a>, <a href="https://arxiv.org/format/1601.03459">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> </div> <p class="title is-5 mathjax"> The Ultimate Display </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Fluke%2C+C+J">C. J. Fluke</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+D+G">D. G. Barnes</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1601.03459v1-abstract-short" style="display: inline;"> Astronomical images and datasets are increasingly high-resolution and multi-dimensional. The vast majority of astronomers perform all of their visualisation and analysis tasks on low-resolution, two-dimensional desktop monitors. If there were no technological barriers to designing the ultimate stereoscopic display for astronomy, what would it look like? What capabilities would we require of our co… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1601.03459v1-abstract-full').style.display = 'inline'; document.getElementById('1601.03459v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1601.03459v1-abstract-full" style="display: none;"> Astronomical images and datasets are increasingly high-resolution and multi-dimensional. The vast majority of astronomers perform all of their visualisation and analysis tasks on low-resolution, two-dimensional desktop monitors. If there were no technological barriers to designing the ultimate stereoscopic display for astronomy, what would it look like? What capabilities would we require of our compute hardware to drive it? And are existing technologies even close to providing a true 3D experience that is compatible with the depth resolution of human stereoscopic vision? We consider the CAVE2 (an 80 Megapixel, hybrid 2D and 3D virtual reality environment directly integrated with a 100 Tflop/s GPU-powered supercomputer) and the Oculus Rift (a low- cost, head-mounted display) as examples at opposite financial ends of the immersive display spectrum. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1601.03459v1-abstract-full').style.display = 'none'; document.getElementById('1601.03459v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 January, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">4 pages, 2 figures, to appear in Proceedings of ADASS XXV (Sydney, Australia; 2015), edited by N. P. F. Lorente & K. Shortridge (San Francisco: ASP), ASP Conf. Series</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1512.00873">arXiv:1512.00873</a> <span> [<a href="https://arxiv.org/pdf/1512.00873">pdf</a>, <a href="https://arxiv.org/ps/1512.00873">ps</a>, <a href="https://arxiv.org/format/1512.00873">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> </div> <p class="title is-5 mathjax"> New systemic radial velocities of suspected RR Lyrae binary stars </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Guggenberger%2C+E">Elisabeth Guggenberger</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+T+G">Thomas G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Kolenberg%2C+K">Katrien Kolenberg</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1512.00873v1-abstract-short" style="display: inline;"> Among the tens of thousands of known RR Lyrae stars there are only a handful that show indications of possible binarity. The question why this is the case is still unsolved, and has recently sparked several studies dedicated to the search for additional RR Lyraes in binary systems. Such systems are particularly valuable because they might allow to constrain the stellar mass. Most of the recent stu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1512.00873v1-abstract-full').style.display = 'inline'; document.getElementById('1512.00873v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1512.00873v1-abstract-full" style="display: none;"> Among the tens of thousands of known RR Lyrae stars there are only a handful that show indications of possible binarity. The question why this is the case is still unsolved, and has recently sparked several studies dedicated to the search for additional RR Lyraes in binary systems. Such systems are particularly valuable because they might allow to constrain the stellar mass. Most of the recent studies, however, are based on photometry by finding a light time effect in the timings of maximum light. This approach is a very promising and successful one, but it has a major drawback: by itself, it cannot serve as a definite proof of binarity, because other phenomena such as the Blazhko effect or intrinsic period changes could lead to similar results. Spectroscopic radial velocity measurements, on the other hand, can serve as definite proof of binarity. We have therefore started a project to study spectroscopically RR Lyrae stars that are suspected to be binaries. We have obtained radial velocity (RV) curves with the 2.1m telescope at McDonald observatory. From these we derive systemic RVs which we will compare to previous measurements in order to find changes induced by orbital motions. We also construct templates of the RV curves that can facilitate future studies. We also observed the most promising RR Lyrae binary candidate, TU UMa, as no recent spectroscopic measurements were available. We present a densely covered pulsational RV curve, which will be used to test the predictions of the orbit models that are based on the O-C variations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1512.00873v1-abstract-full').style.display = 'none'; document.getElementById('1512.00873v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 December, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2015. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">4 pages, 1 figure, to appear in the No. 105 issue of the Communications from the Konkoly Observatory of the Hungarian Academy of Sciences</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1511.06500">arXiv:1511.06500</a> <span> [<a href="https://arxiv.org/pdf/1511.06500">pdf</a>, <a href="https://arxiv.org/format/1511.06500">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/0004-637X/823/2/101">10.3847/0004-637X/823/2/101 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Achieving Consistent Doppler Measurements from SDO/HMI Vector Field Inversions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Schuck%2C+P+W">P. W. Schuck</a>, <a href="/search/astro-ph?searchtype=author&query=Antiochos%2C+S">Spiro Antiochos</a>, <a href="/search/astro-ph?searchtype=author&query=Leka%2C+K+D">K. D. Leka</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+G">Graham Barnes</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1511.06500v1-abstract-short" style="display: inline;"> NASA's Solar Dynamics Observatory is delivering vector field observations of the full solar disk with unprecedented temporal and spatial resolution; however, the satellite is in a highly inclined geostationary orbit. The relative spacecraft-Sun velocity varies by $\pm3$~km/s over a day which introduces major orbital artifacts in the Helioseismic Magnetic Imager data. We demonstrate that the orbita… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1511.06500v1-abstract-full').style.display = 'inline'; document.getElementById('1511.06500v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1511.06500v1-abstract-full" style="display: none;"> NASA's Solar Dynamics Observatory is delivering vector field observations of the full solar disk with unprecedented temporal and spatial resolution; however, the satellite is in a highly inclined geostationary orbit. The relative spacecraft-Sun velocity varies by $\pm3$~km/s over a day which introduces major orbital artifacts in the Helioseismic Magnetic Imager data. We demonstrate that the orbital artifacts contaminate all spatial and temporal scales in the data. We describe a newly-developed three stage procedure for mitigating these artifacts in the Doppler data derived from the Milne-Eddington inversions in the HMI Pipeline. This procedure was applied to full disk images of AR11084 to produce consistent Dopplergrams. The data adjustments reduce the power in the orbital artifacts by 31dB. Furthermore, we analyze in detail the corrected images and show that our procedure greatly improve the temporal and spectral properties of the data without adding any new artifacts. We conclude that this new and easily implemented procedure makes a dramatic improvement in the consistency of the HMI data and in its usefulness for precision scientific studies. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1511.06500v1-abstract-full').style.display = 'none'; document.getElementById('1511.06500v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 November, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2015. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">58 pages, 19 figures, submitted to ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1508.05455">arXiv:1508.05455</a> <span> [<a href="https://arxiv.org/pdf/1508.05455">pdf</a>, <a href="https://arxiv.org/format/1508.05455">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/0004-637X/811/2/107">10.1088/0004-637X/811/2/107 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Influence of Spatial Resolution on Nonlinear Force-Free Modeling </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=DeRosa%2C+M+L">M. L. DeRosa</a>, <a href="/search/astro-ph?searchtype=author&query=Wheatland%2C+M+S">M. S. Wheatland</a>, <a href="/search/astro-ph?searchtype=author&query=Leka%2C+K+D">K. D. Leka</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+G">G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Amari%2C+T">T. Amari</a>, <a href="/search/astro-ph?searchtype=author&query=Canou%2C+A">A. Canou</a>, <a href="/search/astro-ph?searchtype=author&query=Gilchrist%2C+S+A">S. A. Gilchrist</a>, <a href="/search/astro-ph?searchtype=author&query=Thalmann%2C+J+K">J. K. Thalmann</a>, <a href="/search/astro-ph?searchtype=author&query=Valori%2C+G">G. Valori</a>, <a href="/search/astro-ph?searchtype=author&query=Wiegelmann%2C+T">T. Wiegelmann</a>, <a href="/search/astro-ph?searchtype=author&query=Schrijver%2C+C+J">C. J. Schrijver</a>, <a href="/search/astro-ph?searchtype=author&query=Malanushenko%2C+A">A. Malanushenko</a>, <a href="/search/astro-ph?searchtype=author&query=Sun%2C+X">X. Sun</a>, <a href="/search/astro-ph?searchtype=author&query=R%C3%A9gnier%2C+S">S. R茅gnier</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1508.05455v1-abstract-short" style="display: inline;"> The nonlinear force-free field (NLFFF) model is often used to describe the solar coronal magnetic field, however a series of earlier studies revealed difficulties in the numerical solution of the model in application to photospheric boundary data. We investigate the sensitivity of the modeling to the spatial resolution of the boundary data, by applying multiple codes that numerically solve the NLF… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1508.05455v1-abstract-full').style.display = 'inline'; document.getElementById('1508.05455v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1508.05455v1-abstract-full" style="display: none;"> The nonlinear force-free field (NLFFF) model is often used to describe the solar coronal magnetic field, however a series of earlier studies revealed difficulties in the numerical solution of the model in application to photospheric boundary data. We investigate the sensitivity of the modeling to the spatial resolution of the boundary data, by applying multiple codes that numerically solve the NLFFF model to a sequence of vector magnetogram data at different resolutions, prepared from a single Hinode/SOT-SP scan of NOAA Active Region 10978 on 2007 December 13. We analyze the resulting energies and relative magnetic helicities, employ a Helmholtz decomposition to characterize divergence errors, and quantify changes made by the codes to the vector magnetogram boundary data in order to be compatible with the force-free model. This study shows that NLFFF modeling results depend quantitatively on the spatial resolution of the input boundary data, and that using more highly resolved boundary data yields more self-consistent results. The free energies of the resulting solutions generally trend higher with increasing resolution, while relative magnetic helicity values vary significantly between resolutions for all methods. All methods require changing the horizontal components, and for some methods also the vertical components, of the vector magnetogram boundary field in excess of nominal uncertainties in the data. The solutions produced by the various methods are significantly different at each resolution level. We continue to recommend verifying agreement between the modeled field lines and corresponding coronal loop images before any NLFFF model is used in a scientific setting. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1508.05455v1-abstract-full').style.display = 'none'; document.getElementById('1508.05455v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 August, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2015. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted to ApJ; comments/corrections to this article are welcome via e-mail, even after publication</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1502.05015">arXiv:1502.05015</a> <span> [<a href="https://arxiv.org/pdf/1502.05015">pdf</a>, <a href="https://arxiv.org/format/1502.05015">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1007/s10686-015-9444-3">10.1007/s10686-015-9444-3 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A Digital-Receiver for the Murchison Widefield Array </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Prabu%2C+T">Thiagaraj Prabu</a>, <a href="/search/astro-ph?searchtype=author&query=Srivani%2C+K+S">K. S. Srivani</a>, <a href="/search/astro-ph?searchtype=author&query=Roshi%2C+D+A">D. Anish Roshi</a>, <a href="/search/astro-ph?searchtype=author&query=Kamini%2C+P+A">P. A. Kamini</a>, <a href="/search/astro-ph?searchtype=author&query=Madhavi%2C+S">S. Madhavi</a>, <a href="/search/astro-ph?searchtype=author&query=Emrich%2C+D">David Emrich</a>, <a href="/search/astro-ph?searchtype=author&query=Crosse%2C+B">Brian Crosse</a>, <a href="/search/astro-ph?searchtype=author&query=Williams%2C+A+J">Andrew J. Williams</a>, <a href="/search/astro-ph?searchtype=author&query=Waterson%2C+M">Mark Waterson</a>, <a href="/search/astro-ph?searchtype=author&query=Deshpande%2C+A+A">Avinash A. Deshpande</a>, <a href="/search/astro-ph?searchtype=author&query=Shankar%2C+N+U">N. Udaya Shankar</a>, <a href="/search/astro-ph?searchtype=author&query=Subrahmanyan%2C+R">Ravi Subrahmanyan</a>, <a href="/search/astro-ph?searchtype=author&query=Briggs%2C+F+H">Frank H. Briggs</a>, <a href="/search/astro-ph?searchtype=author&query=Goeke%2C+R+F">Robert F. Goeke</a>, <a href="/search/astro-ph?searchtype=author&query=Tingay%2C+S+J">Steven J. Tingay</a>, <a href="/search/astro-ph?searchtype=author&query=Johnston-Hollitt%2C+M">Melanie Johnston-Hollitt</a>, <a href="/search/astro-ph?searchtype=author&query=R%2C+G+M">Gopalakrishna M R</a>, <a href="/search/astro-ph?searchtype=author&query=Morgan%2C+E+H">Edward H. Morgan</a>, <a href="/search/astro-ph?searchtype=author&query=Pathikulangara%2C+J">Joseph Pathikulangara</a>, <a href="/search/astro-ph?searchtype=author&query=Bunton%2C+J+D">John D. Bunton</a>, <a href="/search/astro-ph?searchtype=author&query=Hampson%2C+G">Grant Hampson</a>, <a href="/search/astro-ph?searchtype=author&query=Williams%2C+C">Christopher Williams</a>, <a href="/search/astro-ph?searchtype=author&query=Ord%2C+S+M">Stephen M. Ord</a>, <a href="/search/astro-ph?searchtype=author&query=Wayth%2C+R+B">Randall B. Wayth</a>, <a href="/search/astro-ph?searchtype=author&query=Kumar%2C+D">Deepak Kumar</a> , et al. (33 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1502.05015v1-abstract-short" style="display: inline;"> An FPGA-based digital-receiver has been developed for a low-frequency imaging radio interferometer, the Murchison Widefield Array (MWA). The MWA, located at the Murchison Radio-astronomy Observatory (MRO) in Western Australia, consists of 128 dual-polarized aperture-array elements (tiles) operating between 80 and 300\,MHz, with a total processed bandwidth of 30.72 MHz for each polarization. Radio-… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1502.05015v1-abstract-full').style.display = 'inline'; document.getElementById('1502.05015v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1502.05015v1-abstract-full" style="display: none;"> An FPGA-based digital-receiver has been developed for a low-frequency imaging radio interferometer, the Murchison Widefield Array (MWA). The MWA, located at the Murchison Radio-astronomy Observatory (MRO) in Western Australia, consists of 128 dual-polarized aperture-array elements (tiles) operating between 80 and 300\,MHz, with a total processed bandwidth of 30.72 MHz for each polarization. Radio-frequency signals from the tiles are amplified and band limited using analog signal conditioning units; sampled and channelized by digital-receivers. The signals from eight tiles are processed by a single digital-receiver, thus requiring 16 digital-receivers for the MWA. The main function of the digital-receivers is to digitize the broad-band signals from each tile, channelize them to form the sky-band, and transport it through optical fibers to a centrally located correlator for further processing. The digital-receiver firmware also implements functions to measure the signal power, perform power equalization across the band, detect interference-like events, and invoke diagnostic modes. The digital-receiver is controlled by high-level programs running on a single-board-computer. This paper presents the digital-receiver design, implementation, current status, and plans for future enhancements. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1502.05015v1-abstract-full').style.display = 'none'; document.getElementById('1502.05015v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 February, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2015. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">14 pages, 7 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1410.4380">arXiv:1410.4380</a> <span> [<a href="https://arxiv.org/pdf/1410.4380">pdf</a>, <a href="https://arxiv.org/ps/1410.4380">ps</a>, <a href="https://arxiv.org/format/1410.4380">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/stu2044">10.1093/mnras/stu2044 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> An In-Depth Spectroscopic Analysis of RR Lyr Variations over the Pulsation Cycle </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Fossati%2C+L">L. Fossati</a>, <a href="/search/astro-ph?searchtype=author&query=Kolenberg%2C+K">K. Kolenberg</a>, <a href="/search/astro-ph?searchtype=author&query=Shulyak%2C+D+V">D. V. Shulyak</a>, <a href="/search/astro-ph?searchtype=author&query=Elmasli%2C+A">A. Elmasli</a>, <a href="/search/astro-ph?searchtype=author&query=Tsymbal%2C+V">V. Tsymbal</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+T+G">T. G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Guggenberger%2C+E">E. Guggenberger</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1410.4380v1-abstract-short" style="display: inline;"> The stellar parameters of RR Lyrae stars vary considerably over a pulsation cycle, and their determination is crucial for stellar modelling. We present a detailed spectroscopic analysis of the pulsating star RR Lyr, the prototype of its class, over a complete pulsation cycle, based on high-resolution spectra collected at the 2.7-m telescope of McDonald Observatory. We used simultaneous photometry… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1410.4380v1-abstract-full').style.display = 'inline'; document.getElementById('1410.4380v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1410.4380v1-abstract-full" style="display: none;"> The stellar parameters of RR Lyrae stars vary considerably over a pulsation cycle, and their determination is crucial for stellar modelling. We present a detailed spectroscopic analysis of the pulsating star RR Lyr, the prototype of its class, over a complete pulsation cycle, based on high-resolution spectra collected at the 2.7-m telescope of McDonald Observatory. We used simultaneous photometry to determine the accurate pulsation phase of each spectrum and determined the effective temperature, the shape of the depth-dependent microturbulent velocity, and the abundance of several elements, for each phase. The surface gravity was fixed to 2.4. Element abundances resulting from our analysis are stable over the pulsation cycle. However, a variation in ionisation equilibrium is observed around minimum radius. We attribute this mostly to a dynamical acceleration contributing to the surface gravity. Variable turbulent convection on time scales longer than the pulsation cycle has been proposed as a cause for the Blazhko effect. We test this hypothesis to some extent by using the derived variable depth-dependent microturbulent velocity profiles to estimate their effect on the stellar magnitude. These effects turn out to be wavelength-dependent and much smaller than the observed light variations over the Blazhko cycle: if variations in the turbulent motions are entirely responsible for the Blazhko effect, they must surpass the scales covered by the microturbulent velocity. This work demonstrates the possibility of a self-consistent spectroscopic analysis over an entire pulsation cycle using static atmosphere models, provided one takes into account certain features of a rapidly pulsating atmosphere. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1410.4380v1-abstract-full').style.display = 'none'; document.getElementById('1410.4380v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 16 October, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2014. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication on MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1407.4928">arXiv:1407.4928</a> <span> [<a href="https://arxiv.org/pdf/1407.4928">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1126/science.1253645">10.1126/science.1253645 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Echography of young stars reveals their evolution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Zwintz%2C+K">K. Zwintz</a>, <a href="/search/astro-ph?searchtype=author&query=Fossati%2C+L">L. Fossati</a>, <a href="/search/astro-ph?searchtype=author&query=Ryabchikova%2C+T">T. Ryabchikova</a>, <a href="/search/astro-ph?searchtype=author&query=Guenther%2C+D">D. Guenther</a>, <a href="/search/astro-ph?searchtype=author&query=Aerts%2C+C">C. Aerts</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+T+G">T. G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Themessl%2C+N">N. Themessl</a>, <a href="/search/astro-ph?searchtype=author&query=Lorenz%2C+D">D. Lorenz</a>, <a href="/search/astro-ph?searchtype=author&query=Cameron%2C+C">C. Cameron</a>, <a href="/search/astro-ph?searchtype=author&query=Kuschnig%2C+R">R. Kuschnig</a>, <a href="/search/astro-ph?searchtype=author&query=Pollack-Drs%2C+S">S. Pollack-Drs</a>, <a href="/search/astro-ph?searchtype=author&query=Moravveji%2C+E">E. Moravveji</a>, <a href="/search/astro-ph?searchtype=author&query=Baglin%2C+A">A. Baglin</a>, <a href="/search/astro-ph?searchtype=author&query=Matthews%2C+J+M">J. M. Matthews</a>, <a href="/search/astro-ph?searchtype=author&query=Moffat%2C+A+F+J">A. F. J. Moffat</a>, <a href="/search/astro-ph?searchtype=author&query=Poretti%2C+E">E. Poretti</a>, <a href="/search/astro-ph?searchtype=author&query=Rainer%2C+M">M. Rainer</a>, <a href="/search/astro-ph?searchtype=author&query=Rucinski%2C+S+M">S. M. Rucinski</a>, <a href="/search/astro-ph?searchtype=author&query=Sasselov%2C+D">D. Sasselov</a>, <a href="/search/astro-ph?searchtype=author&query=Weiss%2C+W+W">W. W. Weiss</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1407.4928v1-abstract-short" style="display: inline;"> We demonstrate that a seismic analysis of stars in their earliest evolutionary phases is a powerful method to identify young stars and distinguish their evolutionary states. The early star that is born from the gravitational collapse of a molecular cloud reaches at some point sufficient temperature, mass and luminosity to be detected. Accretion stops and the pre-main sequence star that emerges is… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1407.4928v1-abstract-full').style.display = 'inline'; document.getElementById('1407.4928v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1407.4928v1-abstract-full" style="display: none;"> We demonstrate that a seismic analysis of stars in their earliest evolutionary phases is a powerful method to identify young stars and distinguish their evolutionary states. The early star that is born from the gravitational collapse of a molecular cloud reaches at some point sufficient temperature, mass and luminosity to be detected. Accretion stops and the pre-main sequence star that emerges is nearly fully convective and chemically homogeneous. It will continue to contract gravitationally until the density and temperature in the core are high enough to start nuclear burning of hydrogen. We show that there is a relationship between detected pulsation properties for a sample of young stars and their evolutionary status illustrating the potential of asteroseismology for the early evolutionary phases. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1407.4928v1-abstract-full').style.display = 'none'; document.getElementById('1407.4928v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 July, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2014. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">23 pages, 9 figures, includes Supplementary Material. Science, published in Science Express on July 3, 2014</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1404.1881">arXiv:1404.1881</a> <span> [<a href="https://arxiv.org/pdf/1404.1881">pdf</a>, <a href="https://arxiv.org/format/1404.1881">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1007/s11207-014-0516-8">10.1007/s11207-014-0516-8 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: Overview and Performance </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Hoeksema%2C+J+T">J. Todd Hoeksema</a>, <a href="/search/astro-ph?searchtype=author&query=Liu%2C+Y">Yang Liu</a>, <a href="/search/astro-ph?searchtype=author&query=Hayashi%2C+K">Keiji Hayashi</a>, <a href="/search/astro-ph?searchtype=author&query=Sun%2C+X">Xudong Sun</a>, <a href="/search/astro-ph?searchtype=author&query=Schou%2C+J">Jesper Schou</a>, <a href="/search/astro-ph?searchtype=author&query=Couvidat%2C+S">Sebastien Couvidat</a>, <a href="/search/astro-ph?searchtype=author&query=Norton%2C+A">Aimee Norton</a>, <a href="/search/astro-ph?searchtype=author&query=Bobra%2C+M">Monica Bobra</a>, <a href="/search/astro-ph?searchtype=author&query=Centeno%2C+R">Rebecca Centeno</a>, <a href="/search/astro-ph?searchtype=author&query=Leka%2C+K+D">K. D. Leka</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+G">Graham Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Turmon%2C+M+J">Michael J. Turmon</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1404.1881v1-abstract-short" style="display: inline;"> The Helioseismic and Magnetic Imager (HMI) began near-continuous full-disk solar measurements on 1 May 2010 from the Solar Dynamics Observatory (SDO). An automated processing pipeline keeps pace with observations to produce observable quantities, including the photospheric vector magnetic field, from sequences of filtergrams. The primary 720s observables were released in mid 2010, including Stokes… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1404.1881v1-abstract-full').style.display = 'inline'; document.getElementById('1404.1881v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1404.1881v1-abstract-full" style="display: none;"> The Helioseismic and Magnetic Imager (HMI) began near-continuous full-disk solar measurements on 1 May 2010 from the Solar Dynamics Observatory (SDO). An automated processing pipeline keeps pace with observations to produce observable quantities, including the photospheric vector magnetic field, from sequences of filtergrams. The primary 720s observables were released in mid 2010, including Stokes polarization parameters measured at six wavelengths as well as intensity, Doppler velocity, and the line-of-sight magnetic field. More advanced products, including the full vector magnetic field, are now available. Automatically identified HMI Active Region Patches (HARPs) track the location and shape of magnetic regions throughout their lifetime. The vector field is computed using the Very Fast Inversion of the Stokes Vector (VFISV) code optimized for the HMI pipeline; the remaining 180 degree azimuth ambiguity is resolved with the Minimum Energy (ME0) code. The Milne-Eddington inversion is performed on all full-disk HMI observations. The disambiguation, until recently run only on HARP regions, is now implemented for the full disk. Vector and scalar quantities in the patches are used to derive active region indices potentially useful for forecasting; the data maps and indices are collected in the SHARP data series, hmi.sharp_720s. Patches are provided in both CCD and heliographic coordinates. HMI provides continuous coverage of the vector field, but has modest spatial, spectral, and temporal resolution. Coupled with limitations of the analysis and interpretation techniques, effects of the orbital velocity, and instrument performance, the resulting measurements have a certain dynamic range and sensitivity and are subject to systematic errors and uncertainties that are characterized in this report. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1404.1881v1-abstract-full').style.display = 'none'; document.getElementById('1404.1881v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 April, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2014. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">42 pages, 19 figures, accepted to Solar Physics</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1404.1879">arXiv:1404.1879</a> <span> [<a href="https://arxiv.org/pdf/1404.1879">pdf</a>, <a href="https://arxiv.org/format/1404.1879">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1007/s11207-014-0529-3">10.1007/s11207-014-0529-3 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: SHARPs -- Space-weather HMI Active Region Patches </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Bobra%2C+M+G">Monica G. Bobra</a>, <a href="/search/astro-ph?searchtype=author&query=Sun%2C+X">Xudong Sun</a>, <a href="/search/astro-ph?searchtype=author&query=Hoeksema%2C+J+T">J. Todd Hoeksema</a>, <a href="/search/astro-ph?searchtype=author&query=Turmon%2C+M+J">Michael J. Turmon</a>, <a href="/search/astro-ph?searchtype=author&query=Liu%2C+Y">Yang Liu</a>, <a href="/search/astro-ph?searchtype=author&query=Hayashi%2C+K">Keiji Hayashi</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+G">Graham Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Leka%2C+K+D">K. D. Leka</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1404.1879v1-abstract-short" style="display: inline;"> A new data product from the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) called Space-weather HMI Active Region Patches (SHARPs) is now available. SDO/HMI is the first space-based instrument to map the full-disk photospheric vector magnetic field with high cadence and continuity. The SHARP data series provide maps in patches that encompass automatically track… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1404.1879v1-abstract-full').style.display = 'inline'; document.getElementById('1404.1879v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1404.1879v1-abstract-full" style="display: none;"> A new data product from the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) called Space-weather HMI Active Region Patches (SHARPs) is now available. SDO/HMI is the first space-based instrument to map the full-disk photospheric vector magnetic field with high cadence and continuity. The SHARP data series provide maps in patches that encompass automatically tracked magnetic concentrations for their entire lifetime; map quantities include the photospheric vector magnetic field and its uncertainty, along with Doppler velocity, continuum intensity, and line-of-sight magnetic field. Furthermore, keywords in the SHARP data series provide several parameters that concisely characterize the magnetic-field distribution and its deviation from a potential-field configuration. These indices may be useful for active-region event forecasting and for identifying regions of interest. The indices are calculated per patch and are available on a twelve-minute cadence. Quick-look data are available within approximately three hours of observation; definitive science products are produced approximately five weeks later. SHARP data are available at http://jsoc.stanford.edu and maps are available in either of two different coordinate systems. This article describes the SHARP data products and presents examples of SHARP data and parameters. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1404.1879v1-abstract-full').style.display = 'none'; document.getElementById('1404.1879v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 April, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2014. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">27 pages, 7 figures. Accepted to Solar Physics</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1403.3677">arXiv:1403.3677</a> <span> [<a href="https://arxiv.org/pdf/1403.3677">pdf</a>, <a href="https://arxiv.org/ps/1403.3677">ps</a>, <a href="https://arxiv.org/format/1403.3677">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1007/s11207-014-0497-7">10.1007/s11207-014-0497-7 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: Optimization of the Spectral Line Inversion Code </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Centeno%2C+R">R. Centeno</a>, <a href="/search/astro-ph?searchtype=author&query=Schou%2C+J">J. Schou</a>, <a href="/search/astro-ph?searchtype=author&query=Hayashi%2C+K">K. Hayashi</a>, <a href="/search/astro-ph?searchtype=author&query=Norton%2C+A">A. Norton</a>, <a href="/search/astro-ph?searchtype=author&query=Hoeksema%2C+J+T">J. T. Hoeksema</a>, <a href="/search/astro-ph?searchtype=author&query=Liu%2C+Y">Y. Liu</a>, <a href="/search/astro-ph?searchtype=author&query=Leka%2C+K+D">K. D. Leka</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+G">G. Barnes</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1403.3677v1-abstract-short" style="display: inline;"> The Very Fast Inversion of the Stokes Vector (VFISV) is a Milne-Eddington spectral line inversion code used to determine the magnetic and thermodynamic parameters of the solar photosphere from observations of the Stokes vector in the 6173 A Fe I line by the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO). We report on the modifications made to the original VFISV… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1403.3677v1-abstract-full').style.display = 'inline'; document.getElementById('1403.3677v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1403.3677v1-abstract-full" style="display: none;"> The Very Fast Inversion of the Stokes Vector (VFISV) is a Milne-Eddington spectral line inversion code used to determine the magnetic and thermodynamic parameters of the solar photosphere from observations of the Stokes vector in the 6173 A Fe I line by the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO). We report on the modifications made to the original VFISV inversion code in order to optimize its operation within the HMI data pipeline and provide the smoothest solution in active regions. The changes either sped up the computation or reduced the frequency with which the algorithm failed to converge to a satisfactory solution. Additionally, coding bugs which were detected and fixed in the original VFISV release, are reported here. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1403.3677v1-abstract-full').style.display = 'none'; document.getElementById('1403.3677v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 March, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2014. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in Solar Physics</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1401.5494">arXiv:1401.5494</a> <span> [<a href="https://arxiv.org/pdf/1401.5494">pdf</a>, <a href="https://arxiv.org/ps/1401.5494">ps</a>, <a href="https://arxiv.org/format/1401.5494">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/201323214">10.1051/0004-6361/201323214 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Two spotted and magnetic early B-type stars in the young open cluster NGC2264 discovered by MOST and ESPaDOnS </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Fossati%2C+L">L. Fossati</a>, <a href="/search/astro-ph?searchtype=author&query=Zwintz%2C+K">K. Zwintz</a>, <a href="/search/astro-ph?searchtype=author&query=Castro%2C+N">N. Castro</a>, <a href="/search/astro-ph?searchtype=author&query=Langer%2C+N">N. Langer</a>, <a href="/search/astro-ph?searchtype=author&query=Lorenz%2C+D">D. Lorenz</a>, <a href="/search/astro-ph?searchtype=author&query=Schneider%2C+F+R+N">F. R. N. Schneider</a>, <a href="/search/astro-ph?searchtype=author&query=Kuschnig%2C+R">R. Kuschnig</a>, <a href="/search/astro-ph?searchtype=author&query=Matthews%2C+J+M">J. M. Matthews</a>, <a href="/search/astro-ph?searchtype=author&query=Alecian%2C+E">E. Alecian</a>, <a href="/search/astro-ph?searchtype=author&query=Wade%2C+G+A">G. A. Wade</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+T+G">T. G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Thoul%2C+A+A">A. A. Thoul</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1401.5494v1-abstract-short" style="display: inline;"> Star clusters are known as superb tools for understanding stellar evolution. In a quest for understanding the physical origin of magnetism and chemical peculiarity in about 7% of the massive main-sequence stars, we analysed two of the ten brightest members of the ~10 Myr old Galactic open cluster NGC 2264, the early B-dwarfs HD47887 and HD47777. We find accurate rotation periods of 1.95 and 2.64 d… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1401.5494v1-abstract-full').style.display = 'inline'; document.getElementById('1401.5494v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1401.5494v1-abstract-full" style="display: none;"> Star clusters are known as superb tools for understanding stellar evolution. In a quest for understanding the physical origin of magnetism and chemical peculiarity in about 7% of the massive main-sequence stars, we analysed two of the ten brightest members of the ~10 Myr old Galactic open cluster NGC 2264, the early B-dwarfs HD47887 and HD47777. We find accurate rotation periods of 1.95 and 2.64 days, respectively, from MOST photometry. We obtained ESPaDOnS spectropolarimetric observations, through which we determined stellar parameters, detailed chemical surface abundances, projected rotational velocities, and the inclination angles of the rotation axis. Because we found only small (<5 km/s) radial velocity variations, most likely caused by spots, we can rule out that HD47887 and HD47777 are close binaries. Finally, using the least-squares deconvolution technique, we found that both stars possess a large-scale magnetic field with an average longitudinal field strength of about 400 G. From a simultaneous fit of the stellar parameters we determine the evolutionary masses of HD47887 and HD47777 to be 9.4+/-0.7 M0 and 7.6+/-0.5 M0. Interestingly, HD47777 shows a remarkable helium underabundance, typical of helium-weak chemically peculiar stars, while the abundances of HD47887 are normal, which might imply that diffusion is operating in the lower mass star but not in the slightly more massive one. Furthermore, we argue that the rather slow rotation, as well as the lack of nitrogen enrichment in both stars, can be consistent with both the fossil and the binary hypothesis for the origin of the magnetic field. However, the presence of two magnetic and apparently single stars near the top of the cluster mass-function may speak in favour of the latter. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1401.5494v1-abstract-full').style.display = 'none'; document.getElementById('1401.5494v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 January, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2014. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">13 pages, accepted for publication on A&A</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1310.2414">arXiv:1310.2414</a> <span> [<a href="https://arxiv.org/pdf/1310.2414">pdf</a>, <a href="https://arxiv.org/format/1310.2414">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Cosmology and Nongalactic Astrophysics">astro-ph.CO</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1017/pasa.2013.36">10.1017/pasa.2013.36 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A New 1.4GHz Radio Continuum Map of the Sky South of Declination +25 deg </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Calabretta%2C+M+R">Mark R. Calabretta</a>, <a href="/search/astro-ph?searchtype=author&query=Staveley-Smith%2C+L">Lister Staveley-Smith</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+D+G">David G. Barnes</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1310.2414v1-abstract-short" style="display: inline;"> Archival data from the HI Parkes All-Sky Survey (HIPASS) and the HI Zone of Avoidance (HIZOA) survey have been carefully reprocessed into a new 1.4GHz continuum map of the sky south of declination +25 deg. The wide sky coverage, high sensitivity of 40mK (limited by confusion), resolution of 14'.4 (compared to 51' for the Haslam et al. 408MHz and 35' for the Reich et al. 1.4GHz surveys), and low le… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1310.2414v1-abstract-full').style.display = 'inline'; document.getElementById('1310.2414v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1310.2414v1-abstract-full" style="display: none;"> Archival data from the HI Parkes All-Sky Survey (HIPASS) and the HI Zone of Avoidance (HIZOA) survey have been carefully reprocessed into a new 1.4GHz continuum map of the sky south of declination +25 deg. The wide sky coverage, high sensitivity of 40mK (limited by confusion), resolution of 14'.4 (compared to 51' for the Haslam et al. 408MHz and 35' for the Reich et al. 1.4GHz surveys), and low level of artefacts makes this map ideal for numerous studies, including: merging into interferometer maps to complete large-scale structures; decomposition of thermal and non-thermal emission components from Galactic and extragalactic sources; and comparison of emission regions with other frequencies. The new map is available for download. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1310.2414v1-abstract-full').style.display = 'none'; document.getElementById('1310.2414v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 October, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2013. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">30 pages, 17 figures, 4 tables. Publications of the Astronomical Society of Australia, in press. Data products available from http://www.atnf.csiro.au/research/CHIPASS/</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1309.0916">arXiv:1309.0916</a> <span> [<a href="https://arxiv.org/pdf/1309.0916">pdf</a>, <a href="https://arxiv.org/format/1309.0916">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Cosmology and Nongalactic Astrophysics">astro-ph.CO</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/stt1662">10.1093/mnras/stt1662 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The giant lobes of Centaurus A observed at 118 MHz with the Murchison Widefield Array </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=McKinley%2C+B">B. McKinley</a>, <a href="/search/astro-ph?searchtype=author&query=Briggs%2C+F">F. Briggs</a>, <a href="/search/astro-ph?searchtype=author&query=Gaensler%2C+B+M">B. M. Gaensler</a>, <a href="/search/astro-ph?searchtype=author&query=Feain%2C+I+J">I. J. Feain</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardi%2C+G">G. Bernardi</a>, <a href="/search/astro-ph?searchtype=author&query=Wayth%2C+R+B">R. B. Wayth</a>, <a href="/search/astro-ph?searchtype=author&query=Johnston-Hollitt%2C+M">M. Johnston-Hollitt</a>, <a href="/search/astro-ph?searchtype=author&query=Offringa%2C+A+R">A. R. Offringa</a>, <a href="/search/astro-ph?searchtype=author&query=Arcus%2C+W">W. Arcus</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+D+G">D. G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Bowman%2C+J+D">J. D. Bowman</a>, <a href="/search/astro-ph?searchtype=author&query=Bunton%2C+J+D">J. D. Bunton</a>, <a href="/search/astro-ph?searchtype=author&query=Cappallo%2C+R+J">R. J. Cappallo</a>, <a href="/search/astro-ph?searchtype=author&query=Corey%2C+B+E">B. E. Corey</a>, <a href="/search/astro-ph?searchtype=author&query=Deshpande%2C+A">A. Deshpande</a>, <a href="/search/astro-ph?searchtype=author&query=deSouza%2C+L">L. deSouza</a>, <a href="/search/astro-ph?searchtype=author&query=Emrich%2C+D">D. Emrich</a>, <a href="/search/astro-ph?searchtype=author&query=Goeke%2C+R">R. Goeke</a>, <a href="/search/astro-ph?searchtype=author&query=Greenhill%2C+L+J">L. J. Greenhill</a>, <a href="/search/astro-ph?searchtype=author&query=Hazelton%2C+B+J">B. J. Hazelton</a>, <a href="/search/astro-ph?searchtype=author&query=Herne%2C+D">D. Herne</a>, <a href="/search/astro-ph?searchtype=author&query=Hewitt%2C+J+N">J. N. Hewitt</a>, <a href="/search/astro-ph?searchtype=author&query=Kaplan%2C+D+L">D. L. Kaplan</a>, <a href="/search/astro-ph?searchtype=author&query=Kasper%2C+J+C">J. C. Kasper</a>, <a href="/search/astro-ph?searchtype=author&query=Kincaid%2C+B+B">B. B. Kincaid</a> , et al. (28 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1309.0916v1-abstract-short" style="display: inline;"> We present new wide-field observations of Centaurus A (Cen A) and the surrounding region at 118 MHz with the Murchison Widefield Array (MWA) 32-tile prototype, with which we investigate the spectral-index distribution of Cen A's giant radio lobes. We compare our images to 1.4 GHz maps of Cen A and compute spectral indices using temperature-temperature plots and spectral tomography. We find that th… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1309.0916v1-abstract-full').style.display = 'inline'; document.getElementById('1309.0916v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1309.0916v1-abstract-full" style="display: none;"> We present new wide-field observations of Centaurus A (Cen A) and the surrounding region at 118 MHz with the Murchison Widefield Array (MWA) 32-tile prototype, with which we investigate the spectral-index distribution of Cen A's giant radio lobes. We compare our images to 1.4 GHz maps of Cen A and compute spectral indices using temperature-temperature plots and spectral tomography. We find that the morphologies at 118 MHz and 1.4 GHz match very closely apart from an extra peak in the southern lobe at 118 MHz, which provides tentative evidence for the existence of a southern counterpart to the northern middle lobe of Cen A. Our spatially-averaged spectral indices for both the northern and southern lobes are consistent with previous analyses, however we find significant spatial variation of the spectra across the extent of each lobe. Both the spectral-index distribution and the morphology at low radio frequencies support a scenario of multiple outbursts of activity from the central engine. Our results are consistent with inverse-Compton modelling of radio and gamma-ray data that supports a value for the lobe age of between 10 and 80 Myr. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1309.0916v1-abstract-full').style.display = 'none'; document.getElementById('1309.0916v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 September, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2013. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">18 pages, 11 figures, accepted for publication in MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1308.2742">arXiv:1308.2742</a> <span> [<a href="https://arxiv.org/pdf/1308.2742">pdf</a>, <a href="https://arxiv.org/format/1308.2742">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/0004-6256/146/4/103">10.1088/0004-6256/146/4/103 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> On the detection and tracking of space debris using the Murchison Widefield Array. I. Simulations and test observations demonstrate feasibility </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Tingay%2C+S+J">S. J. Tingay</a>, <a href="/search/astro-ph?searchtype=author&query=Kaplan%2C+D+L">D. L. Kaplan</a>, <a href="/search/astro-ph?searchtype=author&query=McKinley%2C+B">B. McKinley</a>, <a href="/search/astro-ph?searchtype=author&query=Briggs%2C+F">F. Briggs</a>, <a href="/search/astro-ph?searchtype=author&query=Wayth%2C+R+B">R. B. Wayth</a>, <a href="/search/astro-ph?searchtype=author&query=Hurley-Walker%2C+N">N. Hurley-Walker</a>, <a href="/search/astro-ph?searchtype=author&query=Kennewell%2C+J">J. Kennewell</a>, <a href="/search/astro-ph?searchtype=author&query=Smith%2C+C">C. Smith</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+K">K. Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Arcus%2C+W">W. Arcus</a>, <a href="/search/astro-ph?searchtype=author&query=Bhat%2C+R">R. Bhat</a>, <a href="/search/astro-ph?searchtype=author&query=Emrich%2C+D">D. Emrich</a>, <a href="/search/astro-ph?searchtype=author&query=Herne%2C+D">D. Herne</a>, <a href="/search/astro-ph?searchtype=author&query=Kudryavtseva%2C+N">N. Kudryavtseva</a>, <a href="/search/astro-ph?searchtype=author&query=Lynch%2C+M">M. Lynch</a>, <a href="/search/astro-ph?searchtype=author&query=Ord%2C+S+M">S. M. Ord</a>, <a href="/search/astro-ph?searchtype=author&query=Waterson%2C+M">M. Waterson</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+D+G">D. G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Bell%2C+M">M. Bell</a>, <a href="/search/astro-ph?searchtype=author&query=Gaensler%2C+B+M">B. M. Gaensler</a>, <a href="/search/astro-ph?searchtype=author&query=Lenc%2C+E">E. Lenc</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardi%2C+G">G. Bernardi</a>, <a href="/search/astro-ph?searchtype=author&query=Greenhill%2C+L+J">L. J. Greenhill</a>, <a href="/search/astro-ph?searchtype=author&query=Kasper%2C+J+C">J. C. Kasper</a>, <a href="/search/astro-ph?searchtype=author&query=Bowman%2C+J+D">J. D. Bowman</a> , et al. (38 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1308.2742v1-abstract-short" style="display: inline;"> The Murchison Widefield Array (MWA) is a new low frequency interferomeric radio telescope. The MWA is the low frequency precursor to the Square Kilometre Array (SKA) and is the first of three SKA precursors to be operational, supporting a varied science mission ranging from the attempted detection of the Epoch of Reionisation to the monitoring of solar flares and space weather. We explore the poss… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1308.2742v1-abstract-full').style.display = 'inline'; document.getElementById('1308.2742v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1308.2742v1-abstract-full" style="display: none;"> The Murchison Widefield Array (MWA) is a new low frequency interferomeric radio telescope. The MWA is the low frequency precursor to the Square Kilometre Array (SKA) and is the first of three SKA precursors to be operational, supporting a varied science mission ranging from the attempted detection of the Epoch of Reionisation to the monitoring of solar flares and space weather. We explore the possibility that the MWA can be used for the purposes of Space Situational Awareness (SSA). In particular we propose that the MWA can be used as an element of a passive radar facility operating in the frequency range 87.5 - 108 MHz (the commercial FM broadcast band). In this scenario the MWA can be considered the receiving element in a bi-static radar configuration, with FM broadcast stations serving as non-cooperative transmitters. The FM broadcasts propagate into space, are reflected off debris in Earth orbit, and are received at the MWA. The imaging capabilities of the MWA can be used to simultaneously detect multiple pieces of space debris, image their positions on the sky as a function of time, and provide tracking data that can be used to determine orbital parameters. Such a capability would be a valuable addition to Australian and global SSA assets, in terms of southern and eastern hemispheric coverage. We provide a feasibility assessment of this proposal, based on simple calculations and electromagnetic simulations that shows the detection of sub-metre size debris should be possible (debris radius of >0.5 m to ~1000 km altitude). We also present a proof-of-concept set of observations that demonstrate the feasibility of the proposal, based on the detection and tracking of the International Space Station via reflected FM broadcast signals originating in south-west Western Australia. These observations broadly validate our calculations and simulations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1308.2742v1-abstract-full').style.display = 'none'; document.getElementById('1308.2742v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 August, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2013. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">24 pages, 5 figures, accepted by The Astronomical Journal. Abstract abridged here due to character number limits</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1307.1938">arXiv:1307.1938</a> <span> [<a href="https://arxiv.org/pdf/1307.1938">pdf</a>, <a href="https://arxiv.org/ps/1307.1938">ps</a>, <a href="https://arxiv.org/format/1307.1938">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/0004-637X/786/1/19">10.1088/0004-637X/786/1/19 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Helioseismology of Pre-Emerging Active Regions III: Statistical Analysis </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+G">G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Birch%2C+A+C">A. C. Birch</a>, <a href="/search/astro-ph?searchtype=author&query=Leka%2C+K+D">K. D. Leka</a>, <a href="/search/astro-ph?searchtype=author&query=Braun%2C+D+C">D. C. Braun</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1307.1938v1-abstract-short" style="display: inline;"> The subsurface properties of active regions prior to their appearance at the solar surface may shed light on the process of active region formation. Helioseismic holography has been applied to samples taken from two populations of regions on the Sun (pre-emergence and without emergence), each sample having over 100 members, that were selected to minimize systematic bias, as described in Paper I (L… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1307.1938v1-abstract-full').style.display = 'inline'; document.getElementById('1307.1938v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1307.1938v1-abstract-full" style="display: none;"> The subsurface properties of active regions prior to their appearance at the solar surface may shed light on the process of active region formation. Helioseismic holography has been applied to samples taken from two populations of regions on the Sun (pre-emergence and without emergence), each sample having over 100 members, that were selected to minimize systematic bias, as described in Paper I (Leka et al., 2012). Paper II (Birch et al., 2012) showed that there are statistically significant signatures in the average helioseismic properties that precede the formation of an active region. This paper describes a more detailed analysis of the samples of pre-emergence regions and regions without emergence, based on discriminant analysis. The property that is best able to distinguish the populations is found to be the surface magnetic field, even a day before the emergence time. However, after accounting for the correlations between the surface field and the quantities derived from helioseismology, there is still evidence of a helioseismic precursor to active region emergence that is present for at least a day prior to emergence. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1307.1938v1-abstract-full').style.display = 'none'; document.getElementById('1307.1938v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 July, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2013. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Submitted to ApJ</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ApJ, 786, 19 (2014) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1305.6047">arXiv:1305.6047</a> <span> [<a href="https://arxiv.org/pdf/1305.6047">pdf</a>, <a href="https://arxiv.org/format/1305.6047">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Cosmology and Nongalactic Astrophysics">astro-ph.CO</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/0004-637X/771/2/105">10.1088/0004-637X/771/2/105 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A 189 MHz, 2400 square degree polarization survey with the Murchison Widefield Array 32-element prototype </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Bernardi%2C+G">G. Bernardi</a>, <a href="/search/astro-ph?searchtype=author&query=Greenhill%2C+L+J">L. J. Greenhill</a>, <a href="/search/astro-ph?searchtype=author&query=Mitchell%2C+D+A">D. A. Mitchell</a>, <a href="/search/astro-ph?searchtype=author&query=Ord%2C+S+M">S. M. Ord</a>, <a href="/search/astro-ph?searchtype=author&query=Hazelton%2C+B+J">B. J. Hazelton</a>, <a href="/search/astro-ph?searchtype=author&query=Gaensler%2C+B+M">B. M. Gaensler</a>, <a href="/search/astro-ph?searchtype=author&query=de+Oliveira-Costa%2C+A">A. de Oliveira-Costa</a>, <a href="/search/astro-ph?searchtype=author&query=Morales%2C+M+F">M. F. Morales</a>, <a href="/search/astro-ph?searchtype=author&query=Shankar%2C+N+U">N. Udaya Shankar</a>, <a href="/search/astro-ph?searchtype=author&query=Subrahmanyan%2C+R">R. Subrahmanyan</a>, <a href="/search/astro-ph?searchtype=author&query=Wayth%2C+R+B">R. B. Wayth</a>, <a href="/search/astro-ph?searchtype=author&query=Lenc%2C+E">E. Lenc</a>, <a href="/search/astro-ph?searchtype=author&query=Williams%2C+C+L">C. L. Williams</a>, <a href="/search/astro-ph?searchtype=author&query=Arcus%2C+W">W. Arcus</a>, <a href="/search/astro-ph?searchtype=author&query=Arora%2C+S+B">S. B. Arora</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+D+G">D. G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Bowman%2C+J+D">J. D. Bowman</a>, <a href="/search/astro-ph?searchtype=author&query=Briggs%2C+F+H">F. H. Briggs</a>, <a href="/search/astro-ph?searchtype=author&query=Bunton%2C+J+D">J. D. Bunton</a>, <a href="/search/astro-ph?searchtype=author&query=Cappallo%2C+R+J">R. J. Cappallo</a>, <a href="/search/astro-ph?searchtype=author&query=Corey%2C+B+E">B. E. Corey</a>, <a href="/search/astro-ph?searchtype=author&query=Deshpande%2C+A">A. Deshpande</a>, <a href="/search/astro-ph?searchtype=author&query=deSouza%2C+L">L. deSouza</a>, <a href="/search/astro-ph?searchtype=author&query=Emrich%2C+D">D. Emrich</a>, <a href="/search/astro-ph?searchtype=author&query=Goeke%2C+R">R. Goeke</a> , et al. (28 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1305.6047v3-abstract-short" style="display: inline;"> We present a Stokes I, Q and U survey at 189 MHz with the Murchison Widefield Array 32-element prototype covering 2400 square degrees. The survey has a 15.6 arcmin angular resolution and achieves a noise level of 15 mJy/beam. We demonstrate a novel interferometric data analysis that involves calibration of drift scan data, integration through the co-addition of warped snapshot images and deconvolu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1305.6047v3-abstract-full').style.display = 'inline'; document.getElementById('1305.6047v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1305.6047v3-abstract-full" style="display: none;"> We present a Stokes I, Q and U survey at 189 MHz with the Murchison Widefield Array 32-element prototype covering 2400 square degrees. The survey has a 15.6 arcmin angular resolution and achieves a noise level of 15 mJy/beam. We demonstrate a novel interferometric data analysis that involves calibration of drift scan data, integration through the co-addition of warped snapshot images and deconvolution of the point spread function through forward modeling. We present a point source catalogue down to a flux limit of 4 Jy. We detect polarization from only one of the sources, PMN J0351-2744, at a level of 1.8 \pm 0.4%, whereas the remaining sources have a polarization fraction below 2%. Compared to a reported average value of 7% at 1.4 GHz, the polarization fraction of compact sources significantly decreases at low frequencies. We find a wealth of diffuse polarized emission across a large area of the survey with a maximum peak of ~13 K, primarily with positive rotation measure values smaller than +10 rad/m^2. The small values observed indicate that the emission is likely to have a local origin (closer than a few hundred parsecs). There is a large sky area at 2^h30^m where the diffuse polarized emission rms is fainter than 1 K. Within this area of low Galactic polarization we characterize the foreground properties in a cold sky patch at $(伪,未) = (4^h,-27^\circ.6)$ in terms of three dimensional power spectra <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1305.6047v3-abstract-full').style.display = 'none'; document.getElementById('1305.6047v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 June, 2013; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 26 May, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2013. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">18 pages, 14 figures. Accepted for publication in ApJ. A version with high resolution figures is available at http://www.astro.rug.nl/~bernardi/32T_survey/32T_survey.pdf</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1303.1433">arXiv:1303.1433</a> <span> [<a href="https://arxiv.org/pdf/1303.1433">pdf</a>, <a href="https://arxiv.org/format/1303.1433">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/0004-637X/762/2/130">10.1088/0004-637X/762/2/130 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Helioseismology of Pre-Emerging Active Regions I: Overview, Data, and Target Selection Criteria </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Leka%2C+K+D">K. D. Leka</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+G">G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Birch%2C+A+C">A. C. Birch</a>, <a href="/search/astro-ph?searchtype=author&query=Gonzalez-Hernandez%2C+I">I. Gonzalez-Hernandez</a>, <a href="/search/astro-ph?searchtype=author&query=Dunn%2C+T">T. Dunn</a>, <a href="/search/astro-ph?searchtype=author&query=Javornik%2C+B">B. Javornik</a>, <a href="/search/astro-ph?searchtype=author&query=Braun%2C+D+C">D. C. Braun</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1303.1433v1-abstract-short" style="display: inline;"> This first paper in a series describes the design of a study testing whether pre-appearance signatures of solar magnetic active regions were detectable using various tools of local helioseismology. The ultimate goal is to understand flux-emergence mechanisms by setting observational constraints on pre-appearance subsurface changes, for comparison with results from simulation efforts. This first pa… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1303.1433v1-abstract-full').style.display = 'inline'; document.getElementById('1303.1433v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1303.1433v1-abstract-full" style="display: none;"> This first paper in a series describes the design of a study testing whether pre-appearance signatures of solar magnetic active regions were detectable using various tools of local helioseismology. The ultimate goal is to understand flux-emergence mechanisms by setting observational constraints on pre-appearance subsurface changes, for comparison with results from simulation efforts. This first paper provides details of the data selection and preparation of the samples, each containing over 100 members, of two populations: regions on the Sun that produced a numbered NOAA active region, and a "control" sample of areas that did not. The seismology is performed on data from the GONG network; accompanying magnetic data from SOHO/MDI are used for co-temporal analysis of the surface magnetic field. Samples are drawn from 2001 -- 2007, and each target is analyzed for 27.7 hr prior to an objectively determined time of emergence. The results of two analysis approaches are published separately: one based on averages of the seismology- and magnetic-derived signals over the samples, another based on Discriminant Analysis of these signals, for a statistical test of detectable differences between the two populations. We include here descriptions of a new potential-field calculation approach and the algorithm for matching sample distributions over multiple variables. We describe known sources of bias and the approaches used to mitigate them. We also describe unexpected bias sources uncovered during the course of the study and include a discussion of refinements that should be included in future work on this topic. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1303.1433v1-abstract-full').style.display = 'none'; document.getElementById('1303.1433v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 March, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2013. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">24 pages, 11 figures, 2 tables. Published in ApJ</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> The Astrophysical Journal, Volume 762, Issue 2, article id. 130, 15 pp. (2013) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1303.1391">arXiv:1303.1391</a> <span> [<a href="https://arxiv.org/pdf/1303.1391">pdf</a>, <a href="https://arxiv.org/format/1303.1391">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/0004-637X/762/2/131">10.1088/0004-637X/762/2/131 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Helioseismology of Pre-Emerging Active Regions II: Average Emergence Properties </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Birch%2C+A+C">A. C. Birch</a>, <a href="/search/astro-ph?searchtype=author&query=Braun%2C+D+C">D. C. Braun</a>, <a href="/search/astro-ph?searchtype=author&query=Leka%2C+K+D">K. D. Leka</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+G">G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Javornik%2C+B">B. Javornik</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1303.1391v1-abstract-short" style="display: inline;"> We report on average subsurface properties of pre-emerging active regions as compared to areas where no active region emergence was detected. Helioseismic holography is applied to samples of the two populations (pre-emergence and without emergence), each sample having over 100 members, which were selected to minimize systematic bias, as described in Leka et al. We find that there are statistically… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1303.1391v1-abstract-full').style.display = 'inline'; document.getElementById('1303.1391v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1303.1391v1-abstract-full" style="display: none;"> We report on average subsurface properties of pre-emerging active regions as compared to areas where no active region emergence was detected. Helioseismic holography is applied to samples of the two populations (pre-emergence and without emergence), each sample having over 100 members, which were selected to minimize systematic bias, as described in Leka et al. We find that there are statistically significant signatures (i.e., difference in the means of more than a few standard errors) in the average subsurface flows and the apparent wave speed that precede the formation of an active region. The measurements here rule out spatially extended flows of more than about 15 m/s in the top 20 Mm below the photosphere over the course of the day preceding the start of visible emergence. These measurements place strong constraints on models of active region formation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1303.1391v1-abstract-full').style.display = 'none'; document.getElementById('1303.1391v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 March, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2013. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">15 pages, 10 figures, ApJ (published)</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> The Astrophysical Journal, Volume 762, Issue 2, article id. 131, 12 pp. (2013) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1302.3369">arXiv:1302.3369</a> <span> [<a href="https://arxiv.org/pdf/1302.3369">pdf</a>, <a href="https://arxiv.org/ps/1302.3369">ps</a>, <a href="https://arxiv.org/format/1302.3369">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/201220934">10.1051/0004-6361/201220934 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Regular frequency patterns in the young delta Scuti star HD 261711 observed by the CoRoT and MOST satellites </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Zwintz%2C+K">K. Zwintz</a>, <a href="/search/astro-ph?searchtype=author&query=Fossati%2C+L">L. Fossati</a>, <a href="/search/astro-ph?searchtype=author&query=Guenther%2C+D+B">D. B. Guenther</a>, <a href="/search/astro-ph?searchtype=author&query=Ryabchikova%2C+T">T. Ryabchikova</a>, <a href="/search/astro-ph?searchtype=author&query=Baglin%2C+A">A. Baglin</a>, <a href="/search/astro-ph?searchtype=author&query=Themessl%2C+N">N. Themessl</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+T+G">T. G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Matthews%2C+J+M">J. M. Matthews</a>, <a href="/search/astro-ph?searchtype=author&query=Auvergne%2C+M">M. Auvergne</a>, <a href="/search/astro-ph?searchtype=author&query=Bohlender%2C+D">D. Bohlender</a>, <a href="/search/astro-ph?searchtype=author&query=Chaintreuil%2C+S">S. Chaintreuil</a>, <a href="/search/astro-ph?searchtype=author&query=Kuschnig%2C+R">R. Kuschnig</a>, <a href="/search/astro-ph?searchtype=author&query=Moffat%2C+A+F+J">A. F. J. Moffat</a>, <a href="/search/astro-ph?searchtype=author&query=Rowe%2C+J+F">J. F. Rowe</a>, <a href="/search/astro-ph?searchtype=author&query=Rucinski%2C+S+M">S. M. Rucinski</a>, <a href="/search/astro-ph?searchtype=author&query=Sasselov%2C+D">D. Sasselov</a>, <a href="/search/astro-ph?searchtype=author&query=Weiss%2C+W+W">W. W. Weiss</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1302.3369v1-abstract-short" style="display: inline;"> We concentrate on an asteroseismological study of HD 261711, a rather hot delta Scuti type pulsating member of the young open cluster NGC 2264 located at the blue border of the instability region. HD 261711 was discovered to be a pre-main sequence delta Scuti star using the time series photometry obtained by the MOST satellite in 2006. High-precision, time-series photometry of HD 261711 was obtain… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1302.3369v1-abstract-full').style.display = 'inline'; document.getElementById('1302.3369v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1302.3369v1-abstract-full" style="display: none;"> We concentrate on an asteroseismological study of HD 261711, a rather hot delta Scuti type pulsating member of the young open cluster NGC 2264 located at the blue border of the instability region. HD 261711 was discovered to be a pre-main sequence delta Scuti star using the time series photometry obtained by the MOST satellite in 2006. High-precision, time-series photometry of HD 261711 was obtained by the MOST and CoRoT satellites in 4 separate new observing runs that are put into context with the star's fundamental atmospheric parameters obtained from spectroscopy. With the new MOST data set from 2011/12 and the two CoRoT light curves from 2008 and 2011/12, the delta Scuti variability was confirmed and regular groups of frequencies were discovered. The two pulsation frequencies identified in the data from the first MOST observing run in 2006 are confirmed and 23 new delta Scuti-type frequencies were discovered using the CoRoT data. Weighted average frequencies for each group are related to l=0 and l=1 p-modes. Evidence for amplitude modulation of the frequencies in two groups is seen. The effective temperature was derived to be 8600$\pm$200 K, log g is 4.1$\pm$0.2, and the projected rotational velocity is 53$\pm$1km/s. Using our Teff value and the radius of 1.8$\pm$0.5 Rsun derived from SED fitting, we get a log L/Lsun of 1.20$\pm$0.14 which agrees well to the seismologically determined values of 1.65 Rsun and, hence, a log L/Lsun of 1.13. The radial velocity of 14$\pm$2 km/s we derived for HD 261711, confirms the star's membership to NGC 2264. Our asteroseismic models suggest that HD 261711 is a delta Scuti-type star close to the zero-age main sequence (ZAMS) with a mass of 1.8 to 1.9Msun. HD 261711 is either a young ZAMS star or a late PMS star just before the onset of hydrogen-core burning. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1302.3369v1-abstract-full').style.display = 'none'; document.getElementById('1302.3369v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 February, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2013. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages, 13 figures, A&A accepted</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1301.0991">arXiv:1301.0991</a> <span> [<a href="https://arxiv.org/pdf/1301.0991">pdf</a>, <a href="https://arxiv.org/ps/1301.0991">ps</a>, <a href="https://arxiv.org/format/1301.0991">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/201220127">10.1051/0004-6361/201220127 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> gamma Doradus pulsation in two pre-main sequence stars discovered by CoRoT </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Zwintz%2C+K">K. Zwintz</a>, <a href="/search/astro-ph?searchtype=author&query=Fossati%2C+L">L. Fossati</a>, <a href="/search/astro-ph?searchtype=author&query=Ryabchikova%2C+T">T. Ryabchikova</a>, <a href="/search/astro-ph?searchtype=author&query=Kaiser%2C+A">A. Kaiser</a>, <a href="/search/astro-ph?searchtype=author&query=Gruberbauer%2C+M">M. Gruberbauer</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+T+G">T. G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Baglin%2C+A">A. Baglin</a>, <a href="/search/astro-ph?searchtype=author&query=Chaintreuil%2C+S">S. Chaintreuil</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1301.0991v1-abstract-short" style="display: inline;"> Pulsations in pre-main sequence stars have been discovered several times within the last years. But nearly all of these pulsators are of delta Scuti-type. gamma Doradus-type pulsation in young stars has been predicted by theory, but lack observational evidence. We present the investigation of variability caused by rotation and (gammaDoradus-type) pulsation in two pre-main sequence members of the y… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1301.0991v1-abstract-full').style.display = 'inline'; document.getElementById('1301.0991v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1301.0991v1-abstract-full" style="display: none;"> Pulsations in pre-main sequence stars have been discovered several times within the last years. But nearly all of these pulsators are of delta Scuti-type. gamma Doradus-type pulsation in young stars has been predicted by theory, but lack observational evidence. We present the investigation of variability caused by rotation and (gammaDoradus-type) pulsation in two pre-main sequence members of the young open cluster NGC2264 using high-precision time series photometry from the CoRoT satellite and dedicated high-resolution spectroscopy. Time series photometry of NGC2264VAS20 and NGC 2264VAS87 was obtained by the CoRoT satellite during the dedicated short run SRa01 in March 2008. NGC2264VAS87 was re-observed by CoRoT during the short run SRa05 in December 2011 and January 2012. Frequency analysis was conducted using Period04 and SigSpec. The spectral analysis was performed using equivalent widths and spectral synthesis. The frequency analysis yielded 10 and 14 intrinsic frequencies for NGC2264VAS20 and NGC2264VAS 87, respectively, in the range from 0 to 1.5c/d which are attributed to be caused by a combination of rotation and pulsation. The effective temperatures were derived to be 6380$\pm$150K for NGC2264VAS20 and 6220$\pm$150K for NGC2264VAS87. Membership of the two stars to the cluster is confirmed independently using X-ray fluxes, radial velocity measurements and proper motions available in the literature. The derived Li abundances of log n(Li)=3.34 and 3.54 for NGC2264VAS20 and NGC2264VAS87, respectively, are in agreement with the Li abundance for other stars in NGC2264 of similar Teff reported in the literature. We conclude that the two objects are members of NGC2264 and therefore are in their pre-main sequence evolutionary stage. Assuming that part of their variability is caused by pulsation, these two stars might be the first pre-main sequence gamma Doradus candidates. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1301.0991v1-abstract-full').style.display = 'none'; document.getElementById('1301.0991v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 January, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2013. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 10 figures, A&A accepted</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1212.5151">arXiv:1212.5151</a> <span> [<a href="https://arxiv.org/pdf/1212.5151">pdf</a>, <a href="https://arxiv.org/format/1212.5151">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Cosmology and Nongalactic Astrophysics">astro-ph.CO</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1017/pas.2013.009">10.1017/pas.2013.009 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Science with the Murchison Widefield Array </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Bowman%2C+J+D">Judd D. Bowman</a>, <a href="/search/astro-ph?searchtype=author&query=Cairns%2C+I">Iver Cairns</a>, <a href="/search/astro-ph?searchtype=author&query=Kaplan%2C+D+L">David L. Kaplan</a>, <a href="/search/astro-ph?searchtype=author&query=Murphy%2C+T">Tara Murphy</a>, <a href="/search/astro-ph?searchtype=author&query=Oberoi%2C+D">Divya Oberoi</a>, <a href="/search/astro-ph?searchtype=author&query=Staveley-Smith%2C+L">Lister Staveley-Smith</a>, <a href="/search/astro-ph?searchtype=author&query=Arcus%2C+W">Wayne Arcus</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+D+G">David G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardi%2C+G">Gianni Bernardi</a>, <a href="/search/astro-ph?searchtype=author&query=Briggs%2C+F+H">Frank H. Briggs</a>, <a href="/search/astro-ph?searchtype=author&query=Brown%2C+S">Shea Brown</a>, <a href="/search/astro-ph?searchtype=author&query=Bunton%2C+J+D">John D. Bunton</a>, <a href="/search/astro-ph?searchtype=author&query=Burgasser%2C+A+J">Adam J. Burgasser</a>, <a href="/search/astro-ph?searchtype=author&query=Cappallo%2C+R+J">Roger J. Cappallo</a>, <a href="/search/astro-ph?searchtype=author&query=Chatterjee%2C+S">Shami Chatterjee</a>, <a href="/search/astro-ph?searchtype=author&query=Corey%2C+B+E">Brian E. Corey</a>, <a href="/search/astro-ph?searchtype=author&query=Coster%2C+A">Anthea Coster</a>, <a href="/search/astro-ph?searchtype=author&query=Deshpande%2C+A">Avinash Deshpande</a>, <a href="/search/astro-ph?searchtype=author&query=deSouza%2C+L">Ludi deSouza</a>, <a href="/search/astro-ph?searchtype=author&query=Emrich%2C+D">David Emrich</a>, <a href="/search/astro-ph?searchtype=author&query=Erickson%2C+P">Philip Erickson</a>, <a href="/search/astro-ph?searchtype=author&query=Goeke%2C+R+F">Robert F. Goeke</a>, <a href="/search/astro-ph?searchtype=author&query=Gaensler%2C+B+M">B. M. Gaensler</a>, <a href="/search/astro-ph?searchtype=author&query=Greenhill%2C+L+J">Lincoln J. Greenhill</a>, <a href="/search/astro-ph?searchtype=author&query=Harvey-Smith%2C+L">Lisa Harvey-Smith</a> , et al. (36 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1212.5151v2-abstract-short" style="display: inline;"> Significant new opportunities for astrophysics and cosmology have been identified at low radio frequencies. The Murchison Widefield Array is the first telescope in the Southern Hemisphere designed specifically to explore the low-frequency astronomical sky between 80 and 300 MHz with arcminute angular resolution and high survey efficiency. The telescope will enable new advances along four key scien… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1212.5151v2-abstract-full').style.display = 'inline'; document.getElementById('1212.5151v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1212.5151v2-abstract-full" style="display: none;"> Significant new opportunities for astrophysics and cosmology have been identified at low radio frequencies. The Murchison Widefield Array is the first telescope in the Southern Hemisphere designed specifically to explore the low-frequency astronomical sky between 80 and 300 MHz with arcminute angular resolution and high survey efficiency. The telescope will enable new advances along four key science themes, including searching for redshifted 21 cm emission from the epoch of reionisation in the early Universe; Galactic and extragalactic all-sky southern hemisphere surveys; time-domain astrophysics; and solar, heliospheric, and ionospheric science and space weather. The Murchison Widefield Array is located in Western Australia at the site of the planned Square Kilometre Array (SKA) low-band telescope and is the only low-frequency SKA precursor facility. In this paper, we review the performance properties of the Murchison Widefield Array and describe its primary scientific objectives. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1212.5151v2-abstract-full').style.display = 'none'; document.getElementById('1212.5151v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 February, 2013; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 20 December, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2012. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Updated with revisions. 32 pages including figures and references. Submitted to PASA</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1211.4896">arXiv:1211.4896</a> <span> [<a href="https://arxiv.org/pdf/1211.4896">pdf</a>, <a href="https://arxiv.org/format/1211.4896">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Distributed, Parallel, and Cluster Computing">cs.DC</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Graphics">cs.GR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/sts513">10.1093/mnras/sts513 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Tera-scale Astronomical Data Analysis and Visualization </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Hassan%2C+A+H">A. H. Hassan</a>, <a href="/search/astro-ph?searchtype=author&query=Fluke%2C+C+J">C. J. Fluke</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+D+G">D. G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Kilborn%2C+V+A">V. A. Kilborn</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1211.4896v1-abstract-short" style="display: inline;"> We present a high-performance, graphics processing unit (GPU)-based framework for the efficient analysis and visualization of (nearly) terabyte (TB)-sized 3-dimensional images. Using a cluster of 96 GPUs, we demonstrate for a 0.5 TB image: (1) volume rendering using an arbitrary transfer function at 7--10 frames per second; (2) computation of basic global image statistics such as the mean intensit… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1211.4896v1-abstract-full').style.display = 'inline'; document.getElementById('1211.4896v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1211.4896v1-abstract-full" style="display: none;"> We present a high-performance, graphics processing unit (GPU)-based framework for the efficient analysis and visualization of (nearly) terabyte (TB)-sized 3-dimensional images. Using a cluster of 96 GPUs, we demonstrate for a 0.5 TB image: (1) volume rendering using an arbitrary transfer function at 7--10 frames per second; (2) computation of basic global image statistics such as the mean intensity and standard deviation in 1.7 s; (3) evaluation of the image histogram in 4 s; and (4) evaluation of the global image median intensity in just 45 s. Our measured results correspond to a raw computational throughput approaching one teravoxel per second, and are 10--100 times faster than the best possible performance with traditional single-node, multi-core CPU implementations. A scalability analysis shows the framework will scale well to images sized 1 TB and beyond. Other parallel data analysis algorithms can be added to the framework with relative ease, and accordingly, we present our framework as a possible solution to the image analysis and visualization requirements of next-generation telescopes, including the forthcoming Square Kilometre Array pathfinder radiotelescopes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1211.4896v1-abstract-full').style.display = 'none'; document.getElementById('1211.4896v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 November, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2012. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">16 pages, 14 Figures, accepted for publication in Monthly Notices of the Royal Astronomical Society</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1210.7150">arXiv:1210.7150</a> <span> [<a href="https://arxiv.org/pdf/1210.7150">pdf</a>, <a href="https://arxiv.org/ps/1210.7150">ps</a>, <a href="https://arxiv.org/format/1210.7150">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Cosmology and Nongalactic Astrophysics">astro-ph.CO</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1017/S1743921312021266">10.1017/S1743921312021266 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Cepheid distances from the Baade-Wesselink method </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Gieren%2C+W">Wolfgang Gieren</a>, <a href="/search/astro-ph?searchtype=author&query=Storm%2C+J">Jesper Storm</a>, <a href="/search/astro-ph?searchtype=author&query=Nardetto%2C+N">Nicolas Nardetto</a>, <a href="/search/astro-ph?searchtype=author&query=Gallenne%2C+A">Alexandre Gallenne</a>, <a href="/search/astro-ph?searchtype=author&query=Pietrzy%C5%84ski%2C+G">Grzegorz Pietrzy艅ski</a>, <a href="/search/astro-ph?searchtype=author&query=Fouqu%C3%A9%2C+P">Pascal Fouqu茅</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+T+G">Thomas G. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Majaess%2C+D">Daniel Majaess</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1210.7150v1-abstract-short" style="display: inline;"> Recent progress on Baade-Wesselink (BW)-type techniques to determine the distances to classical Cepheids is reviewed. Particular emphasis is placed on the near-infrared surface-brightness (IRSB) version of the BW method. Its most recent calibration is described and shown to be capable of yielding individual Cepheid distances accurate to 6%, including systematic uncertainties. Cepheid distances fro… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1210.7150v1-abstract-full').style.display = 'inline'; document.getElementById('1210.7150v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1210.7150v1-abstract-full" style="display: none;"> Recent progress on Baade-Wesselink (BW)-type techniques to determine the distances to classical Cepheids is reviewed. Particular emphasis is placed on the near-infrared surface-brightness (IRSB) version of the BW method. Its most recent calibration is described and shown to be capable of yielding individual Cepheid distances accurate to 6%, including systematic uncertainties. Cepheid distances from the IRSB method are compared to those determined from open cluster zero-age main-sequence fitting for Cepheids located in Galactic open clusters, yielding excellent agreement between the IRSB and cluster Cepheid distance scales. Results for the Cepheid period-luminosity (PL) relation in near-infrared and optical bands based on IRSB distances and the question of the universality of the Cepheid PL relation are discussed. Results from other implementations of the BW method are compared to the IRSB distance scale and possible reasons for discrepancies are identified. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1210.7150v1-abstract-full').style.display = 'none'; document.getElementById('1210.7150v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 October, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2012. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Advancing the Physics of Cosmic Distances, Proceedings IAU Symposium No. 289, 2012</span> </p> </li> </ol> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" 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